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Centre Específic de Recerca de

Mètodes Numèrics en Ciències Aplicades i Enginyeria

2014 ANNUAL REPORT

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DESCRIPTION 5

Mission Statement 7

Research Goals 7

PERSONNEL 9

Research Team 11

PhD Students 13

Research Assistants 15

Administrative Staff 15

MANAGEMENT & GOVERNANCE 17

Management Committee 19

RESEARCH 21

Selected Research Projects 23

PhD Theses 59

Publications 60

Conference Participation 62

Research Seminars 63

Outreach 64

EQUIPMENT & FACILITIES 69

TRAINING 73

Coordination of graduate programs. 75

Participation in training programs 75

FINANCIAL REPORT 77

DESCRIPTION

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MISSION STATEMENT

The Laboratori de Càlcul Numèric (LaCàN) is a research group of the Universitat Politècnica of Catalunya (UPC) created on 1995. In 2009 the UPC promoted it to a “Centre Específic de Recerca” (unitat acadèmica) because of its scientific productivity and its interdepartamental and intercampus extension. LaCàN is a research group internationally recognized and the Catalan Government has awarded its maximum research recognition continuously since its first call.

CER-LaCàN is a young and dynamic research group; it is composed by a total of 14 tenured professors (9 of then below 40 years old), several post-doc researchers, 21 PhD students. It is also a highly international group with: 11 foreign PhD students, 6 faculty obtained their PhD degree in US, British or Italian universities.

The group is diverse in terms of the basic training of its members (engineers, mathematicians, physicists), the research topics and funding sources (industrial projects, cutting-edge research projects, international consortia). However, group members have a powerful common denominator in research and teaching: mathematical modeling, numerical methods, and interest in their applicability.

RESEARCH GOALS

CER-LaCàN mission is to be a reference research unit with scientific and socio-economic impact, with technology transfer to industry and consolidated training in the field of mathematical modeling and numerical simulation in applied sciences and engineering. More specifically, it is important to note that currently, researchers in LaCàN produce quality research, publish in high impact international journals, and consistently receive recognition in the form of awards, invited lectures and editorial boards, as well as citations of their work. Moreover, the level of internationalization is high. However, to be reinforce these aspects, we have identified three major challenges that will benefit from the recruit of a young highly productive researcher with experience in international project:

• Scientific research production must be increased in order to compete with the top research groups in the area. This handicaps: young faculty, inefficient allocation of micro- management tasks, and strong teaching load; can be overcome by full time researcher leading its active group.

• Some of the research under development is incremental in well-established lines. While it is important to consolidate it, it is also crucial to invest resources in creating new lines that put the center at the forefront of research in their field

• It is everyday more difficult to attract top-level talent to cover eligible for PhD scholarships or competitive grants. Bringing new internationally recognized people could improve our visibility.

Continuously and consistently proposing innovative ideas at the frontier of knowledge is the best approach to have a strong impact, attract talent, and achieve high productivity (i.e. to be leaders in our field). Therefore, we promote and support original initiatives that explore new potential lines, despite their risk if they open new horizons

PERSONNEL

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RESEARCH TEAM

DIRECTOR DEPUTY DIRECTOR

Full Professor

ANTONIO

HUERTA

Full Professor

PEDRO

DÍEZ

FACULTY

Associate Professor

IRENE

ARIAS

Associate Professor

MARINO

ARROYO

Lecturer

MARCO

DISCACCIATI

Associate Professor

ROSA

ESTELA

Associate Professor

SONIA

FERNANDEZ-MENDEZ

Associate Professor

ADELINE

DE MONTLAUR

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Associate Professor

JOSÉ

MUÑOZ

Associate Professor

NÚRIA

PARÉS

Lecturer

JORDI

POBLET

Full Professor

ANTONIO RODRÍGUEZ-FERRAN

Associate Professor

JOSEP

SARRATE

Lecturer

SERGIO

ZLOTNIK

POSTDOC RESEARCHERS

AMIR

ABDOLLAHI

DANIEL

MILLÁN

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PhD STUDENTS

ALEKSANDAR ANGELOSKI

NINA

ASADIPOUR

RAQUEL

GARCÍA

ABEL

GARGALLO

CEREN

GÜRKEN

SAQIB

HAMEED

BEHROOZ

HASHEMIAN

OMID

JAVADZADEH

BIN

LI

DAVID

MODESTO

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CHRISTIAN

PECO

NIMA

RABIEI

ESTHER

SALA

ALEJANDRO

TORRES

MILAN

VUKADIN

KUAN

ZHANG

VAHID

ZIAEI

PAYMAN

MOSAFFA

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RESEARCH ASSISTANTS

RAÚL

HOSPITAL

ELOI

RUIZ

ADMINISTRATIVE STAFF

PURI

VILLARES

DAVID

ORTIN

SUSANNA

ALGARRA

IMMA

RIUS

MANAGEMENT & GOVERNANCE

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MANAGEMENT COMMITTEE

Antonio Huerta Director

Pedro Díez Deputy Director

Irene Arias

Marino Arroyo Research Coordinator

Sonia Fernández Mendez

Adeline de Montlaur

José Muñoz SEED Coordinator

Antonio Rodriguez Ferran Recruiting Coordinator

Josep Sarrate ICT Coordinator

Puri Villares Head of Administration

RESEARCH

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SELECTED RESEARCH PROJECTS

List of Research Projects

AAR-based decomposition for computational limit analysis

Adaptive high-order hybridizable discontinuous Galerkin for aeroacoustic problems

Atlas of collective variables: a general remedy to overcome topological obstructions

Automatic subsystem identification in statistical energy analysis

Cell-centred model for the simulation of the curved cellular monolayers

CFD study of a debris diversion platform with applications to hydrokinetic energy production

Coexistence of wrinkles and blisters in supported graphene

Development and Analysis of HDG Formulations for Heterogeneous Problems in Computational Fluid Dynamics

High-order mesh generation for high-accuracy simulations

Mesh generation for naturally fractured reservoirs

Modeling and numerical simulation of tearing of brittle thin sheets

Numerical simulation of undersea acoustic impact of off-shore stations

Real-time evaluation of wave-height in harbors

Rheological model for cell fluidisation process

Simulation and optimization of electric grids: solving the load flow problem

The bipenalty method in computational dynamics

The microscopic stress from molecular dynamics simulations

Viability of the proper generalized decomposition in parameterized geometries for flow problems

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AAR-BASED DECOMPOSITION FOR COMPUTATIONAL LIMIT ANALYSIS

Jose J Muñoz, Nima Rabiei

Limit analysis is relevant in many practical engineering areas such as the design of mechanical structure or the analysis of soil mechanics. The theory of limit analysis assumes a rigid, perfectly-plastic material to model the collapse of a solid that is subjected to a static load distribution. Within this context, the problem of limit analysis is to consider a continuum that is subjected to a fixed force distribution consisting of both volume and surfaces loads. Then the objective is to obtain the maximum multiple of this force distribution that causes the collapse of the body. This multiple is usually called collapse multiplier. This collapse multiplier can be obtained analytically by solving an in finite dimensional nonlinear optimisation problem [1]. Thus the computation of the multiplier requires two steps, the first step is to discretise its corresponding analytical problem by the introduction of finite dimensional spaces and the second step is to solve a nonlinear optimisation problem, which represents the major difficulty and challenge in the numerical solution process. Solving this optimisation problem, which may become very large and computationally expensive in three dimensional problems, is the second important step. Recent techniques have allowed scientists to determine upper and lower bounds of the load factor under which the structure will collapse.

Despite the attractiveness of these results, their application to practical examples is still hampered by the size of the resulting optimisation process. Thus a remedy to this is the use of decomposition methods and to parallelise the corresponding optimisation problem. The aim of this project is to develop a decomposition technique which can reduce the memory requirements and computational cost of this type of problems. For this purpose, we exploit the important feature of the underlying optimisation problem: the objective function contains one

scalar variable . For this, we rewrite the constraints of the problem as the intersection of appropriate sets, and propose efficient algorithmic strategies to iteratively solve the decomposition algorithm.

The proposed algorithm is based on the Averaged Alternating Reflections (AAR) [2], which

is able to find the distance between two sets Z( ) and W( ) (see Figure 1-left). Here, Z( ) and

W( ) are the feasibility sets of two sub-problems. If their intersection s non-empty for a given

value , then this value is globally feasible, as illustrated in Figure 1-right.. The optimum * is

found by finding the maximum load factor that gives a non-empty intersection between W( ) and

Z( ). The methodology has been applied to two-dimensional problems for uniform and non-uniform meshes [3].

Figure 1. Left: AAR method Optimal value of the load factor is the maximum value * such

that the intersection between the feasibility sets Z( ) and W( ) is not empty.

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References:

[1] A.V. Lyamin and S.W. Sloan. Lower bound limit analysis using nonlinear programming. Int. J. Numer. Meth. Eng., 55:576{611, 2002.

[2] H.H. Bauschke and P.L. Combettes. Convex analysis and monotone operator theory in Hilbert spaces. Springer, 2010. [3] N. Rabiei, J.J. Mu~noz. AAR-based decomposition algorithm for nonlinear convex optimisation. Computational Optimization and Applications.( Springer). (Submitted)

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ADAPTIVE HIGH-ORDER HYBRIDIZABLE DISCONTINUOUS GALERKIN FOR AEROACOUSTIC PROBLEMS

A. Huerta1, S. Fernández-Méndez, M. Discacciati, A. Angeloski

Wave propagation and high fidelity CFD are challenging problems present in many engineering applications. Acoustic waves, electromagnetism, and vibrations are examples of physical phenomena that are modeled with wave equations. Helmholtz (for mid-high frequencies with non-constant coefficients in the general case), Euler and Navier-Stokes equations still challenge standard numerical techniques in realistic problems because of loss of the ellipticity, or discontinuities, or computation cost and precision, etc.

The ability and efficiency of high-order approximations has been discussed and proven [1]. In particular, the interest in Discontinuous Galerkin (DG) methods has increased over the past years, because they have proved their suitability to construct robust stabilized high-order numerical schemes on arbitrary unstructured and non-conforming grids for a variety of physical phenomena. More precisely, the Hybridizable Discontinuous Galerkin (HDG) method stands out among all DG methods for implicit schemes, thanks to its stability features, its reduced number of degrees of freedom, and its superconvergence properties.

The work of A. Angeloski shows the success of degree adaptive HDG and Embedded Discontinuous Galerkin technique in wave [2], incompressible flows and acoustic problems. The element-by-element discontinuous approximation, common to all DG methods, enables a straightforward implementation of variable degree computations. In addition, an inexpensive element-by-element post-process provides an HDG superconvergent solution that can be used to define an asymptotically exact error estimator in second order problems. The error estimate or indicator drives an automatic update of the approximation degree in each element, which is aimed at obtaining a uniform error distribution with a user-defined tolerance.

The mean flow and the acoustic component are segregated because the noise source (and frequency) is known and can be imposed and it is assumed not to influence the flow. Acoustic perturbations then are computed solving the linearized Euler equations (LEE) and taking into account a mean flow uncoupled solution. Figure 1 shows results for the noise propagation once the acoustic perturbation (the LEE) is solved

Figure 2 shows the same problem with goal-oriented p-adaptive HDG and EDG solutions compared with the space-time results of the commercial code ACTRAN DGM from Free Field Technologies (MacNeal-Schwendler Corporation-MSC Software, Nastran).

1 Contact: antonio.huerta@upc.edu

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Figure 1. Acoustic perturbation for a turbofan induced noise.

Figure 2. Adaptive solution and comparison of tested methods.

References:

[1] A. Huerta, A. Angeloski, X. Roca, J. Peraire, “Efficiency of high-order elements for continuous and discontinuous Galerkin methods”, Int. J. Numer. Methods. Eng., 96(9), pp. 529–60 (2013).

[2] G. Giorgiani, S. Fernández-Méndez, A. Huerta, “Hybridizable Discontinuous Galerkin with degree adaptivity for the incompressible Navier–Stokes equations”, Comput. Fluids, 98, pp. 196–208 (2014).

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ATLAS OF COLLECTIVE VARIABLES: A GENERAL REMEDY TO OVERCOME TOPOLOGICAL OBSTRUCTIONS

Behrooz Hashemian, Marino Arroyo

Nonlinear dimensionality reduction (NLDR) techniques [1] are increasingly used to visualize molecular trajectories and to create data-driven collective variables for enhanced sampling simulations [2]. The success of these methods relies on their ability to identify the essential degrees of freedom characterizing conformational changes. In this work, we show that NLDR methods face serious obstacles when the underlying collective variables present periodicities, e.g., as a result of proper dihedral angles (Figure 1). Consequently, NLDR methods collapse very distant configurations, thus leading to misinterpretations and inefficiencies in enhanced sampling. Here, we identify this largely overlooked problem [3] and propose a novel methodology, called atlas of collective variables, to overcome it [4].

In this approach, we describe the system differently in different regions of conformational space and provide a framework to describe statistical mechanics of molecular systems in terms of an atlas of partially overlapping CVs. We then present a data-driven method based on nonlinear dimensionality reduction to systematically build atlas of CVs from ensembles representative of molecular flexibility, as illustrated in Figure 2.

Figure 1. Topology and geometry of molecular flexibility of a benchmark molecule, alanine dipeptide, which exhibit topological obstruction as a result of periodicity in two backbone dihedral angles.

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Figure 2: Data-driven algorithm to create an atlas of collective variables for alanine dipeptide starting from an ensemble of molecular. The torus is the three-dimensional representation of its two dihedrals backbones.

References:

[1] J. A. Lee and M. Verleysen, Nonlinear Dimensionality Reduction. New York, NY: Springer New York, 2007.

[2] B. Hashemian, D. Millán, and M. Arroyo, “Modeling and enhanced sampling of molecular systems with smooth and nonlinear data-driven collective variables.,” J. Chem. Phys., vol. 139, no. 21, p. 214101, Dec. 2013.

[3] B. Hashemian and M. Arroyo, “Topological obstructions in the way of data-driven collective variables,” J. Chem. Phys., vol. 142, no. 4, p. 044102, 2015.

[4] B. Hashemian, D. Millán, and M. Arroyo, “Charting molecular free-energy landscapes with an atlas of collective variables,”In preparation., 2015.

(f)1

2

3

4

(a)

(b)

(d)

(h)

(c)

(e) (g)

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AUTOMATIC SUBSYSTEM IDENTIFICATION IN STATISTICAL ENERGY ANALYSIS

C. Díaz-Cereceda, J. Poblet-Puig, A. Rodríguez-Ferran1

Solving vibroacoustic problems is challenging [1]. In statistical energy analysis (SEA), one of the challenges is the division of the system into subsystems. We have developed an automatic methodology for subsystem identification [2]. It consists in dividing the system into cells and grouping them into subsystems via a hierarchical cluster analysis based on the problem eigenmodes. The subsystem distribution corresponds to the optimal grouping of the cells, which is defined in terms of the correlation distance between them. The main advantages of this methodology are its automatic performance and its applicability both to vibratory and vibroacoustic systems. Moreover, the method allows the definition of more than one subsystem in the same geometrical region when required. This is the case of eigenmodes with a very different mechanical response (e.g. out-of-plane or in-plane vibration in shells).

The clustering is performed hierarchically. That means that the cluster elements are grouped progressively, in terms of the correlation distance between them. Once two elements are joined, they create a new element, whose distance to the others is measured as the average distance of the members, see figure 1(a). The elements are paired into binary clusters, and the newly formed elements are grouped into larger clusters until a hierarchical tree (dendrogram) is formed, see figure 1(b).

(a)

(b)

Figure 1. Hierarchical cluster analysis: (a) grouping process; (b) dendrogram

1 Contact: antonio.rodriguez-ferran@upc.edu

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This methodology has been validated by means of simple vibrational and vibroacoustic examples [2]. Consider for instance the T-shaped structure of figure 2. The analysis is based on 37 eigenmodes with eigenfrequencies between 1100 and 1500 Hz. Two different cell sizes are considered: λplate and λplate/2, where λplate is the wavelength of the first mode used in the analysis. Figure 3 shows the optimal division of the structure into three subsystems, and figure 4 the corresponding dendrograms. As expected, the proposed approach confirms intuition: each of the three parts of the T-shaped structure should be treated as a subsystem. This example also illustrates the robustness of the approach with respect to the size of the cells.

Figure 2. T-shaped structure

Figure 3. Division into subsystems for two cell sizes: (a) λplate/2; (b) λplate

Figure 4. Dendrograms for two cell sizes: (a) λplate/2; (b) λplate

References:

[1] A. Sestieri, A. Carcaterra, “Vibroacoustic: The challenges of a mission impossible?”, Mech. Syst. Signal Proc. 34, pp. 1-18 (2013).

[2] C. Díaz-Cereceda, J. Poblet-Puig, A. Rodríguez-Ferran, “Automatic subsystem identification in statistical energy analysis”, Mech. Syst. Signal Proc., 54, pp. 182-194 (2015)

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CELL-CENTRED MODEL FOR THE SIMULATION OF THE CURVED CELLULAR MONOLAYERS

P Mosaffa, N Asadipour, D Millán, A Rodríguez-Ferran JJ Muñoz

Recently, it has become apparent that mechanical stimuli have a key role in governing the dynamics of multicellular systems, among other factors. Hence, the stress state of the cell and its neighbourhood is responsible for cell shape changes during cell migration [1], embryo development [2] or organogenesis [3].

Given the fact above, we aim to develop a computational model to simulate global embrygenetic cell shape changes in phenomena such as invagination and germ-band extension, which are accompanied by cell reorganization and cytoskeleton remodelling. We resort to the cell-centred model of the tissues, where cells are represented by their cell centres, and their mechanical interaction is modelled through active non-linear elastic laws with a dynamically changing resting length. Cell-cell connectivity, which defines also cell-cell neighbourhood, is computed by incorporating a modified Delaunay triangulation, in combination with a mapping technique in order to obtain triangulation on curved manifolds. To obtain cell boundaries, Voronoi tessellation of the Delaunay triangulation is obtained.

The elastic response of the material is defined by a scalar potential associated to each connecting bar element between a pair of cell centres, i.e. the mechanical state of the material is only provided by the cell centres position and, disregarding membrane forces. As a result, mechanical equilibrium within the whole material is provided by balancing the forces at each node, exerted by its neighbours via connecting bar elements holding the applied rheological properties.

Our numerical results show that even a linear elastic cell-cell interaction model may induce a global non-linear response due to the reorganization of the cell connectivities [4]. To mimic the global visco-elastic response of the tissues, this plastic-like behavior is combined with a non-linear rheological law where the resting length depends on the elastic strain. The model is applied to simulate the elongation of planar and curved monolayers (see Fig. 1).

Fig. 1 Left: Deformed curved monolayer. Red dots: cell centers. Green lines: cell-cell connectivity (Delaunay

triangulation). Yellow regions: Voronoi tessellation. Right: displacement-reaction curve.

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References

[1] Brugués, A., Anon, E., Conte, V., Veldhuis, J., Gupta, M., Collombelli, J., Muñoz, J.,

Brodland, G., Ladoux, B., Trepat, X.: Forces driving epithelial wound healing. Nature

Physics 10, 683–690 (2014)

[2] Farge, E.: Mechanical Induction of Twist in the Drosophila Foregut/Stomodeal Primordium

Current Biol. 13, 1365–1377 (2003)

[3] Rauzi, M., Verant, P., Lecuit, T., Lenne, P.F.: Nature and anisotropy of cortical forces

orienting drosophila tissue morphogenesis. Nature Cell Biol. 10, 1401–1410 (2008)

[4] Mosaffa P, Asadipour N, Millán D, Rodríguez-Ferrán A, Muñoz JJ. Cell-centred model for

the simulation of curved cellular monolayersComputational Particle Mechanics (submitted)

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CFD STUDY OF A DEBRIS DIVERSION PLATFORM WITH APPLICATIONS TO HYDROKINETIC ENERGY PRODUCTION

Adeline de Montlaur, Jeremy Kasper & Paul Duboy (AHERC - University of Alaska Fairbanks)

The Alaska Hydrokinetic Energy Research Center (AHERC) is conducting ongoing river technology studies at the Tanana River Tests Site (TRTS) at Nenana, Alaska. TRTS is used to test hydrokinetic power generating devices, and to characterize the river environment under realistic Alaska river conditions. Technology studies at the TRTS include performance tests of a research debris diversion platform (RDDP) at protecting a 5kW new energy hydrokinetic turbine from river debris flows and to determine the effect of RDDP generated river current turbulence on turbine efficiency. Previous tests have shown that the RDDP effectively sheds debris, however, large debris objects can cause RDDP rotation about its mooring point requiring that a stable attachment between the RDDP and protected floating structure be in place to ensure that debris is diverted away from the protected structure.

CFD simulations of the RDDP interaction with the river flow have been conducted with ANSYS® in order to compare current velocity, vorticity and turbulence results. The aim of the study is to obtain a clearer idea of where, that is, at which depth and how far behind the RDDP, a hydrokinetic turbine should be located. Some preliminary results have been presented at [1].

Figure 1: Tanana river test site: research debris diversion platform

Figure 2: Velocity at free surface (left) and vorticity at 0.4m below free surface (right) results of CFD simulation of RDDP

Reference: [1] J. Johnson et al. Alaskan wave and river hydrokinetic energy resource assessment, river energy converter testing and surface debris mitigation performance, AGU Fall Meeting, San Francisco 15-19 December 2014

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COEXISTENCE OF WRINKLES AND BLISTERS IN SUPPORTED GRAPHENE

Kuan Zhang and Marino Arroyo

We examine the mechanics of bubbles in supported graphene. In experiments, graphene bubbles have been observed with different sizes and shapes. The reported radii of the circular edges of quasi-spherical bubbles range from dozens of nanometers to several microns (1). Gas released from the substrate can become trapped under the impermeable graphene sample, creating a significant pressure difference across the membrane that produces and stabilizes tense bubbles (2). The amount of gas inside the interstitial space can be used to control the size of bubbles (1). Moreover, blisters with straight edges have been observed, possibly in association with wrinkles (3). Triangular and quadrangular straight-edged bubbles have been observed and controlled by an external electric field (4). It has been shown that a small triangular bubble can generate a very large pseudo-magnetic field, demonstrating that the electronic structure of graphene can be strain engineered. Figure [1] (a-d) shows experimental observations of bubbles of different morphology in supported graphene samples.

The mechanics of quasi-spherical bubbles has been previously examined in detail. However, the mechanism leading to straight-edged bubbles remains unexplored, despite numerous experimental observations. Furthermore, the coexistence and interaction between wrinkles and blisters has not been investigated. In this project, we attempt to address these issues, see our simulations in Figure [1] (e-h) and provide a unified picture of bubbles and wrinkles in supported graphene.

Figure 1: (a-c) AFM topography scan of triangular, quadrangular and circular bubbles. (d) A representative AFM image of straight-edged bubbles coexisting with wrinkles. Our simulations on graphene bubbles with various configurations: (e) a circular bubble, (f) a quadrangular straight-edged bubble, (g) a triangular straight-edged bubble, and (h) a lenticular bubble.

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References:

[1] Koenig, S. P., N. G. Boddeti, M. L. Dunn, and J. S. Bunch (2011). Ultrastrong adhesion of graphene membranes. Nat Nano 6, 543-546.

[2] Bunch, J. S., S. S. Verbridge, J. S. Alden, A. M. van der Zande, J. M. Parpia, H. G. Craighead, and P. L. McEuen (2008). Impermeable atomic membranes from graphene sheets. Nano Letters 8 (8), 2458-2462.

[3] Pan, W., J. Xiao, J. Zhu, C. Yu, G. Zhang, Z. Ni, K. Watanabe, T. Taniguchi, Y. Shi, and X. Wang (2012). Biaxial compressive strain engineering in graphene/boron nitride heterostructures. Sci. Rep. 2, 893.

[4] Georgiou, T., L. Britnell, P. Blake, R. V. Gorbachev, A. Gholinia, A. K. Geim, C. Casiraghi, and K. S. Novoselov (2011). Graphene bubbles with controllable curvature. Applied Physics Letters 99 (9), 093103.

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DEVELOPMENT AND ANALYSIS OF HDG FORMULATIONS FOR HETEROGENEOUS PROBLEMS IN COMPUTATIONAL FLUID DYNAMICS

Sonia Fernández-Méndez, Adeline de Montlaur, Esther Sala-Lardies, Ceren Gürkan, Santiago Arias (EETAC-UPC), Martin Kronbichler (TUM)

This project focuses on the development and analysis of new high-order finite element formulations for heterogeneous problems, with special emphasis on bi-material flow problems.

The new formulations are based on two advanced numerical techniques that are nowadays receiving much attention in the Computer Fluid Dynamics (CFD) community: the Hybridizable Discontinuous Galerkin (HDG, [1,2]) method and eXtended Finite Elements (X-FEM, [3-5]). HDG is a novel efficient discontinuous finite element method that has proved its outstanding efficiency for high-order CFD computations. X-FEM is a clever strategy for the treatment of discontinuities across material interfaces, allowing the presence of interfaces inside the elements.

This project aims to take advantage of the HDG superconvergence properties in the context of heterogeneous problems. The main objective is therefore the development, analysis and application of HDG formulations with material interfaces defined by a level-set representation. The X-FEM philosophy is introduced in an HDG formulation. The solution is enriched with Heaviside functions and, in the case of weak discontinuities, continuity is weakly imposed, emulating the imposition of continuity across element boundaries in standard HDG.

The formulation is first being developed for elliptic problems and then will be extended to Stokes and Navier-Stokes equations with moving interfaces. The formulation will finally be applied to the simulation of generation and dynamics of dispersed bubbles in liquid phase, with application to the study of efficient strategies for the treatment of liquid and gas waste.

Preliminary results, developing the method for void problems, have been presented in [6].

Figure 1. Representation of a bimaterial problem and HDG discretization: elements (blue) and sides (black) are cut by the material interface (red)

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Figure 2. Figures from paper in preparation “X-HDG for void problems”.

References:

[1] B. Cockburn, J. Gopalakrishnan, R. Lazarov. “Unified hybridization of discontinuous Galerkin, mixed, and continuous Galerkin methods for second order elliptic problems”, SIAM J. Numer. Anal. 2009.

[2] G. Giorgiani, D. Modesto, S. Fernández-Méndez, A. Huerta, “High-order continuous and discontinuous Galerkin methods for wave problems”, Int. J. Numer. Meth. Fluids, 2013.

[3] T.P. Fries, T. Belytschko, “The extended/generalized finite element method: An overview of the method and its applications”, Int. J. Numer. Meth. Engrg, 2010.

[4] K.W. Cheng, T.P. Fries, “Higher-order XFEM for curved strong and weak discontinuities”, Int. J. Numer. Meth. Engrg, 2010.

[5] E. Sala-Lardies, S. Fernández-Méndez, A. Huerta, “Optimally convergent high-order X-FEM for problems with voids and inclusions”, Proceedings of European Congress on Computational Methods in Applied Sciences and Engineering (ECCOMAS 2012), Vienna, 2012.

[6] C. Gurkan, S. Fernández-Méndez, E. Sala-Lardies and M. Kronbichler,”eXtended Hybridizable Discontinuous Galerkin (X-HDG) for bimaterial problems”, 6th European Conference on Computational Fluid Dynamics (ECFD VI), Barcelona, July 2014.

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HIGH-ORDER MESH GENERATION FOR HIGH-ACCURACY SIMULATIONS

Josep Sarrate, Eloi Ruiz-Gironés, Abel Gargallo-Peiró (BSC-CNS), Xevi Roca (MIT), Jaime Peraire (MIT)

In the last two decades, high-order methods have attracted a remarkable attention from the community of computational methods. This attention has been prompted by the potential of high-order methods to deliver higher accuracy with a lower computational cost than low order methods. However, their application to industrial problems has been hampered by the need to generate 3D curved meshes. Although a mesh for high-order methods can be composed by straight-sided and potentially curved elements, the later are required to approximate adequately the curved domain boundaries and therefore, to preserve the accuracy of high-order the high-order scheme.

The objective of this project is to develop a hierarchical method to generate valid (without tangled elements) and high-quality (with elements of the desired shape) high-order methods. That is, we first generate curved meshes of the desired degree of interpolation on the geometry surfaces, and then we generate the corresponding volumetric high-order mesh of the same degree of interpolation.

The first step of the project was to define a quality measure to quantify the quality of the generated high-order meshes. Therefore, we focus on the definition of quality measures for high-order meshes for 2D (planar), 2D1/2 (surfaces), and 3D (volumes) geometries.

The starting point of our approach is that using a mature linear mesh generator we create a mesh with elements of the desired size and shape. Then, we increase the interpolation degree of the linear mesh and using an optimization-based method we increase the quality of the high-order mesh.

We have applied our approach to generate curved meshes for high-order 2D simulations. For instance, Figure 1 presents a detail of a mesh of interpolation degree 8 used to compute the wave agitation inside the Barcelona harbor.

For industrial applications the CAD surface description is preferred, since CAD models are generated in the design process. Therefore, we extended the method proposed for planar geometries to generate high-order meshes on parameterized surfaces (see Figure 2).

Finally, once all the surface meshes of a given 3D geometry are meshed with curved elements of the desired degree of interpolation, we are able to generate a volumetric high-order mesh. Figure 3 shows a tetrahedral mesh of interpolation degree 4 around a Falcon aircraft.

This is a join research project with Aerospace Computational Design Laboratory of the Massachusetts Institute of Technology.

References

[1] E. Ruiz-Gironés, X. Roca and J. Sarrate. ”Optimizing mesh distortion by hierarchical iteration relocation of the nodes on the CAD entities”. Proceedings of the 23rd International Meshing Roundtable, London, UK. (2014).

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Figure 1. Tetrahedral mesh of interpolation degree 4 around a Falcon aircraft.

Figure 2. Comparison of the initial linear mesh and the final high-order mesh of interpolation degree 6 for a ratchet gear.

[2] A. Gargallo-Peiró, X. Roca, J. Peraire and J. Sarrate. “Optimization of a regularized distortion measure to generate curved high-order unstructured tetrahedral meshes”. Accepted for publication in International Journal for Numerical Methods in Engineering.

[3] A. Gargallo-Peiró, X. Roca, J. Peraire and J. Sarrate. “Distortion and quality measures for validating and generating high-order tetrahedral meshes”. Accepted for publication in Engineering with Computers.

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MESH GENERATION FOR NATURALLY FRACTURED RESERVOIRS

Josep Sarrate , Eloi Ruíz-Gironés, Rafael Montenegro (ULPGC), José Manuel Cascón (USAL)

Enhanced oil recovery in naturally fractured reservoirs is of the major importance for oil industry. Thus, special efforts have been focus on geological characterization and multiphase flow simulations in complex fractured media. Several models have been used to describe multiphase flow in fractured media. In addition, various numerical methods such as finite differences, finite volumes and finite elements, have been used to discretize these models. However, numerical models based on the finite element method have increased the accuracy of these simulations and also improved their computational efficiency. However, their application to real situations, where large reservoirs with tens of geological faults and wells are considered, is hampered by the need of generate a high-fidelity and high-quality discretization of the reservoir.

The objective of this project is to develop a multiplatform meshing library that will be linked to simulation software for analyzing the extraction processes in large reservoirs. This library has to consider that multiple wells and faults can compose the reservoir. Therefore, special attention will be focused on meshing a reservoir composed by several layers of arbitrary shape. In addition, the library has to include refining and coarsening procedures that will be used by the numerical tool in transient simulations.

This is a join research project with the Universidad de Las Palmas de Gran Canaria (ULPGC), Universidad de Salamanca (USAL), and sponsored by Petrosoft S.A.

Figure 1. Tetrahedral mesh for a reservoir.

43

Figure 2. Reconstruction of a fault inside a tetrahedral mesh of a reservoir.

References

[1] Universidad de Las Palmas de Gran Canaria; Universitat Politècnica de Catalunya; Universidad de Salamanca. Informe Abril 2013: Mallador de tetraedros para una superficie de género cero. (2013).

[2] E. Ruiz-Gironés, A. Oliver, J.M. Cascón, J.M. Escobar, J. Sarrate and R. Monenegro. Tetrahedral mesh optimization combining boundary and inner node relocation and adaptive local refinement. 11th World Congress on Computational Mechanics. Barcelona. (2014)

44

MODELING AND NUMERICAL SIMULATION OF TEARING OF BRITTLE THIN SHEETS

Bin Li, Daniel Millán, Marino Arroyo

Thin sheets are very common in nature, technology, and daily life. Tearing refers to the situation in which cracks propagate in a thin sheet driven by out-of-plane forces (mode III) loading. The classical linear elastic fracture mechanics has been successfully applied to understand and predict crack propagation in brittle materials under in-plane tensile (mode I) or shear (mode II) loading. However, this theory is challenged by tearing of thin sheets undergoing large deformations [1].

Geometry, together with the interplay between stretching and bending deformation, leads to non-trivial and rich behaviors [2,3], particularly when the thin film is adhesively coupled to a flat [4] or curved [5] substrate. In a flat substrate the cracks are observed to converge, whereas on a cylindrical substrate the cracks paths can be convergent or divergent depending on the curvature of the substrate, see Figures 1 and 2. The complexity of these problems restricts the analytical solutions to very simplified settings [1], which do not fully explain a wealth of experimental observations.

To explore tearing of thin films, we have developed a model and a computational framework coupling geometrically nonlinear deformations of Kirchhoff-Love thin shells (stretching and bending), fracture mechanics, and adhesion to a curved substrate. The crack propagation in brittle thin sheets is modeled by a variational approach to fracture [6]. Additionally, a cohesive model is used to describe the delamination of thin sheets adhered to substrates [7]. We numerically implement the model with subdivision finite elements [8,9].

Figure 1: Peeling the film adhered on the exterior side of the cylinder leads to convergent cracks.

45

Figure 2: Peeling the film adhered on the interior side of the cylinder leads to divergent cracks

References:

[1] B. Roman, Fracture path in brittle thin sheets: a unifying review on tearing. Int. J. Fracture 182:209–237 (2013).

[2] A. Takei, B. Roman, J. Bico, E. Hamm and F. Melo, Forbidden directions for the fracture of thin anisotropic sheets: an analogy with the wulff plot. Phy. Rev. Lett. 110:144301 (2013).

[3] E. Bayart, A. Boudaoud and M. Adda-Bedia, Finite-distance singularities in the tearing of thin sheets. Phy. Rev. Lett. 106:194301 (2011).

[4] E. Hamm, P. Reis, M. LeBlanc, B. Roman and E. Cerda, Tearing as a test for mechanical characterization of thin adhesive films. Nat. Mater. 7:386–390 (2008).

[5] O. Kruglova, B. Fabian, V. Didier and P. Damman, How geometry controls the tearing of adhesive thin films on curved surfaces. Phy. Rev. Lett. 7:164303 (2011).

[6] B. Bourdin, G.A. Francfort and J.J. Marigo, The variational approach to fracture. J. Elasticity 91:5–148 (2008).

[7] X. P. Xu and A. Needleman, Numerical simulations of fast crack growth in brittle solids. J. Mech. Phys. Solids 42:1397–1434 (1994).

[8] F. Cirak, M. Ortiz and P. Schroder, Subdivision surfaces: a new paradigm for thin-shell finite-element analysis. Int. J. Numer. Meth. Engng. 47:2039–2072 (2000).

[9] F. Cirak and Q. Long, Subdivision shells with exact boundary control and non-manifold geometry, Int. J. Numer. Meth. Engng. 88:897–923 (2011).

46

NUMERICAL SIMULATION OF UNDERSEA ACOUSTIC IMPACT OF OFF-SHORE STATIONS

Josep Sarrate, Pedro Díez, Raúl Hospital

The design and conception of Offshore Power Stations (for wind, wave and tidal energy generation) requires assessing their environmental impact. Specifically, the European Union Strategy Framework Directive (2008) explicitly identifies the underwater noise as an environmental impact, and mentions anthropogenic underwater sound sources as one type of marine pollution that must be controlled.

Marine species are equipped with a variety of hearing mechanisms and specializations. Even more, concrete species has different hearing abilities at different frequencies. Audiograms for fish and marine mammal species point out that the frequency domain ranges from 10 Hz to 100 KHz. Therefore, it is important modeling the effect of the subsea noise on sea mammals and fishes for this frequency range.

The objective of this project is to develop a 3D simulation tool to assess the subsea noise impact of an Offshore Power Station. Specifically, we focus on the modelization aspects of the problem (set up of mathematical equations, identification and quantification of relevant parameters, …) and on the computational details of their implementation.

Modeling the underwater acoustic propagation in the frequency ranges of interest requires solving generalized homogeneous Helmholtz equation (wave number depends on the salinity and hence on the depth) with different types of boundary conditions and geometries (bathymetry patterns).

GFEM method is specially suited for this kind of analysis where the size of the computational domain is large (from hundreds of meters to kilometers) compared with the characteristic wavelength (from centimeters to meters).

The standard polynomial approximation replaced by a new set of approximating functions, which is composed by products of linear polynomials and plane waves, in different sectors sampling all possible directions. In the 3D case, a specific discretization of the planar waves propagation direction is proposed in the sake of avoiding an extremely large number of degrees of freedom. To increase the efficiency and accuracy of the implementation of the GFEM in this context we have developed a semi-analytical integration rule, which is especially well suited to integrate efficiently the terms of the linear systems of equations to be solved. This allows performing realistic simulations using large element sizes at an affordable computational cost.

References

[1] R. Hospital, J Sarrate, P. Díez,, KIC OTS Product 1 Deliverable D1.19. Mathematical modelling and relevant parameters of the underwater noise propagation model. Laboratori de Càlcul Numèric (LaCaN), Universitat Politècnica de Catalunya, Barcelona, Spain. 2013. [2] R. Hospital, J Sarrate, P. Díez, KIC OTS Product 1 Deliverable D1.22. Three-dimensional implementation of the numerical model. Laboratori de Càlcul Numèric (LaCaN), Universitat Politècnica de Catalunya, Barcelona, Spain. 2014.

[3] A. Moura, D. Lopes, E. Cruz, R. Hospital-Bravo, J. Sarrate y P. Díez, Integrated tool for the acoustic assessment and monitoring of marine activities and operations. Proceedings of the 2nd International Conference and Exhibition on Underwater Acoustics, Rhodes, Greece. 2014

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[4] R. Hospital-Bravo, J.Sarrate and P. Díez, Assessing the subsea acoustic impact of offshore power stations using a partition of unity method. 11th World Congress on Computational Mechanics, Barcelona, Spain. 2014

Figure 1. Sound pressure level (dB) for a planar and partially reflecting sea bottom when the noise source has an amplitude of A = 1 Pa (117 dB) at a distance of 10 m from the source.

Figure 2. Sound pressure level (dB) for a planar and partially reflecting sea bottom when two noise sources have an amplitude of A = 1 Pa (117 dB) at a distance of 10

m from the source.

48

REAL-TIME EVALUATION OF WAVE-HEIGHT IN HARBORS

A. Huerta1, D. Modesto, S. Zlotnik, S. Fernández-Méndez

Real-time wave propagation in harbors is needed for design and operations. Control, validation and design optimization for this problem is still a challenge in medium large-sized real harbors because the number of direct simulations is an extremely demanding task. In spite of using a simplified model (the mild slope equation [1]) and reducing the design parameters to: incoming wave-height, direction and period, given a realistic spectrum, the number of required direct simulations becomes prohibitive for real-time decisions. Moreover, at the design face or in inverse problems, when real-time may not be critical, the computational overhead in real problems precludes a complete analysis for all the spectrum of design variables.

Each direct simulation is in itself a numerical challenge because:

1. the problem is defined in unbounded domains but must be solved in a bounded computational one (artificial boundary conditions must be properly implemented taking into account the real bathymetry),

2. the wave equation (scattering problems) is prone to pollution errors (the higher the frequency the worse),

3. small geometric features in real large harbors may be influential in the final result, 4. the wave-height results are very sensitive to small perturbations of the incoming wave

frequency and direction (naïve interpolation of results is not possible), 5. accuracy of the wave-height prediction.

Figure 1. Mataró harbor: wave amplification and 3 computational domains to test absorbing boundary conditions.

The thesis of D. Modesto [2,3] proposes a methodology based on the proper generalized decomposition [3], a reduced order method, which after an off-line stage produces a generalized solution (computational vademecum [4]) of the wave amplification factor for any direction and frequency of the incoming wave; see [5] for an introduction to off-line/on-line proper generalized decomposition approach.

1 Contact: antonio.huerta@upc.edu

49

Figure 2 shows that the wave-height prediction computed in real-time on a mobile device. The interior area of the Mataró harbor is evaluated without using any strong computational resource for any incident frequency.

Figure 2. Real-time evaluation of the wave height of Mataró harbor: comparison between FEM (left column) and PG PGD (right column).

References:

[1] J. Berkhoff, “Computation of combined refraction-diffraction”, in: Proceedings of the 13th Coastal Engineering Conference, Vol. 1, Vancouver, Canada, pp. 471–490 (1972).

[2] D. Modesto, “Real-time wave monitoring for elliptic harbor models: an a priori reduced order approach”, PhD Thesis, Universitat Politècnica de Catalunya (2014).

[3] D. Modesto, S. Zlotnik, A. Huerta, “Proper generalized decomposition for parameterized Helmholtz problems in heterogeneous and unbounded domains: application to harbor agitation”, Comput. Methods Appl. Mech. Eng., accepted (2015).

[4] A. Ammar, B. Mokdad, F. Chinesta, R. Keunings, “A new family of solvers for some classes of multidimensional partial differential equations encountered in kinetic theory modelling of complex fluids”, J. Non-Newton. Fluid Mech. 139(3), pp. 153–176 (2006).

[5] F. Chinesta, A. Leygue, F. Bordeu, J.V. Aguado, E. Cueto, D. González, I. Alfaro, A. Ammar and A. Huerta, “PGD-Based Computational Vademecum for Efficient Design, Optimization and Control”, Arch. Comput. Methods Eng., 20(1), pp. 31-59, (2013).

50

RHEOLOGICAL MODEL FOR CELL FLUIDISATION PROCESS

Jose J Muñoz, Nina Asadipour

Soft active tissues exhibit poroelastic behaviour [1], softening, hardening, and reversible fluidization [2]. Current understanding of these non-linear behaviours is based on several diverse processes taking part at different scales: active protein motors that actuate at the polymeric structure of the cell, (de)polymerization, remodelling of the cytoskeleton, changes in the cytoplasm volume and cell-cell connectivity changes that take place at the tissue level. The aim of this study is to offer a model that can explain these features.

In order to reconstruct tissue dynamics from the multicellular system and represent the reorganisation (remodelling) of the cytoskeleton, we use a cell-centre model, in which each cell is treated as a discrete entity and adjacent cell centres are connected by the poroelastic active element. Neighbouring cells are determined by a modified Delaunay triangulation while cell shapes are determined by a modified Voronoi tessellation (Figure 2, left).

To understand well the mechanical properties of a soft tissue, we developed a poroelastic model that takes into account the underlying active process at the cytoskeleton level, and allows for active and passive cell-cell reorganization and intercalation [3]. Cell-cell interactions are modelled through specific non-linear elastic laws, and coupled active deformations [4]. In this model, a reversible (elastic) deformation and a non-reversible remodelling and lengthening are considered as two combined effects for a deformation of cross-linked actin filaments under a stretch process (Figure 1). Our model is based on dynamical changes of the resting length, in which by controlling different rates of cell porosity, we are able to model reversible softening that has been experimentally observed in biomechanical tests performed on epithelial lung cell monolayers [5].

We have simulated the application of transient stretch to adherent human airway smooth muscle (HASM), as reported in [5], where the stretching triggers cell softening followed by recovery of the initial cell stiffness. A single transient stretch of 4 seconds was applied to a multicellular system (Figure 2, right). After cessation the single transient stretch, the stiffness G’ and the phase angle δ were computed and their results have been compared with experimental data (Figure 2, right).

Figure 1: (A) Schematic of network of actin filaments connected by flexible cross-links. (B) Schematic of a reduced system with two filaments and a cross-link (white circle) under a stretch process. (a) Initial configuration with resting length equal to . (b) Configuration under

an applied load. (c) New unstrained configuration with modified resting length .

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Figure 2: Left: Scheme of the cell-centered model: spheres represent cell nuclei, and red lines the cell boundaries. Right: A single transient stretch drives the phase angle δ up, indicating fluidization of the cytoskeleton.

References:

[1] E. Moeendarbary, L. Valon, M. Fritzsche, A. Harris, D. Moulding, A. Thrasher, E. Stride, L. Mahadevan and G. T. Charras. The cytoplasm of living cells behaves as a poroelastic material, Nature Materials 12, 253–261, 2013. [2] L. Wol, P. Fernandez and K. Kroy, Resolving the Stiffening-Softening Paradox in Cell Mechanics, Vol. 7, e40063, 2012. [3] J. J, Muñoz, V. Conte, N. Asadipour and M. Miodownik, A truss element for modelling reversible softening in living tissues. Mech. Res. Comm., Vol. 49, 44-49, 2013. [4] J. J, Muñoz and S. Albo. Physiology-based model of cell viscoelasticity, Phys. Rev. E, Vol. 88, 012708, 2013. [5] X. Trepat, L. Deng, S. An, D. Navajas, D. Tschumperlin, W. Gerthoffer, J. Butler, J. Fredberg, Universal physical responses to stretch in the living cell, Nature 447, 2007.

52

SIMULATION AND OPTIMIZATION OF ELECTRIC GRIDS: SOLVING THE LOAD FLOW PROBLEM

Raquel García-Blanco, Domenico Borzacchiello, Francisco Chinesta and Pedro Díez

A “Smart Grid” is an efficient management of the electricity that uses computer technology in order to achieve a safe and sustainable electricity supply. They promise to improve the efficiency of power grid systems through incorporating of power generation as distributed generation (DG). The analysis and optimization of smart grids with distributed generators requires performing a large number of power flow simulations, and each of them undergoes solving a nonlinear system of algebraic equations. In practice, the problems to be solved are parameterized. The free parameters (design variables and stochastic dimensions describing the randomness of energy supply and demand) lie in a multidimensional space to be explored.

The application of the Large Time Increment (LATIN) method, in this context is proposed as a nonlinear solver extremely well fitted for the particular nonlinear algebraic system to be solved. It is seen as an alternative to other standard approaches (Newton-Raphson, HELM…). Moreover, the LATIN is also combined with a Proper Generalized Decomposition (PGD) solver, in order to account for the parametric dependence in an explicit manner (location and nominal power of the generators, grid parameters…). The PGD-LATIN solution constitutes a computational vademecum and, accordingly, the exploration of the parametric space in view of solving any optimization problem is reduced to a simple post-processing.

An illustration of the LATIN approach for load-flow problems.

Convergence curves corresponding to the different choices of the parameters

References: B. Stott. Review of load-flow calculation methods. Proceedings of the IEEE, 62(7):916–929, July

1974. F. Milano. Continuous Newton’s method for power flow analysis. Power Systems, IEEE

Transactions on, 24(1):50–57, 2009. P. Ladeveze and J.G. Simmonds. Nonlinear Computational Structural Mechanics: New Approaches

and Non-Incremental Methods of Calcula- tion. Mechanical Engineering Series. Springer New York, 1999.

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THE BIPENALTY METHOD IN COMPUTATIONAL DYNAMICS

A. Rodríguez-Ferran1, J. Hetherington, M. Caramés-Saddler, H. Askes

Penalty methods are a common technique to impose constraints in finite element (FE) analysis. In statics, penalisation consists in adding virtual stiffness to the FE system. However, this approach is not suitable for dynamics, because the increase in the stiffness leads to a decrease in the critical time step of conditionally stable explicit time-integration schemes. To avoid this, we advocate the use of bipenalty methods, i.e. the simultaneous use of stiffness and mass penalties [1-3]. By choosing appropriately the stiffness and mass penalty parameters, the maximum eigenfrequency of the FE system (and, hence, the critical time step) is not changed. This is shown by analysing two generalised eigenvalue problems: the unpenalised problem prior to the imposition of constraints and the bipenalised problem. We provide expressions of the CPR (critical penalty ratio) for different types of finite elements (bars, beams, plane strain/stress quadrilaterals…). To illustrate the generality and versatility of the bipenalty method, we have applied this idea to a number of numerical examples involving one or several one-point [1,2] or multi-point [3] constraints in a variety of applications: restrained displacements in structural dynamics, a one-dimensional contact-impact formulation and a two-dimensional crack propagation analysis.

Figure 1 shows the time evolution of the displacement of a restrained node [2]. If only a mass penalty is used (penalty ratio R=0), the node starts moving at t = 100 s: the constraint is not accurately imposed. With the critical penalty ratio Rcrit, on the other hand, the node is effectively restrained. This example illustrates the superiority of bipenalties over mass penalties alone.

Figure 1. Displacement time history of the restrained node for three penalty ratios.

The bipenalty method is especially attractive in the case of multi-point constraints, which are cumbersome to impose by means of transformation of the system equations. This is the case, for instance, of interface elements in crack propagation analysis, see the four-point bending test of Figure 2. Bipenalty interface elements are placed between the finite elements of the “process window” shown in grey in Figure 2(a). Although the mechanical model is kept very simple and does not take into account damage/cohesion, the curved crack path observed in experiments is correctly captured, see Figure 2(b). Bipenalties have also been applied to contact-impact problems [4].

We have focused on time domain analysis. Other researchers have shown that the bipenalty approach can also be successfully applied to frequency domain analysis [5].

1 Contact: antonio.rodriguez-ferran@upc.edu

54

(a)

(b)

Figure 2. Bipenalty interface elements in crack propagation analysis: (a) problem statement; (b) curved crack

References:

[1] H. Askes, M. Caramés-Saddler, A. Rodríguez-Ferran, “Bipenalty method for time domain computational dynamics”, Proc. R. Soc. A-Math. Phys. Eng. Sci., 466(2117), pp. 1389-1408 (2010).

[2] J. Hetherington, A. Rodríguez-Ferran, H. Askes, “A new bipenalty formulation for ensuring time step stability in time domain computational dynamics”, Int. J. Numer. Methods Eng., 90(3), pp. 269-286 (2012).

[3] J. Hetherington, A. Rodríguez-Ferran, H. Askes, “The bipenalty method for arbitrary multipoint constraints”, Int. J. Numer. Methods Eng., 93(5), pp. 465-482 (2013).

[4] J. Kopačka, D. Gabriel, R. Kolman, J. Plešek, M. Ulbin, “Studies in numerical stability of explicit contact-impact algorithm to the finite element solution of wave propagation problems”, in: Proc. 4th Int. Conf. on Computational Methods in Structural Dynamics and Earthquake Engineering, COMPDYN 2013, pp. 787-800 (2013).

[5] S. Ilanko, L.E. Monterrubio, “Bipenalty method from a frequency domain perspective”, Int. J. Numer. Methods Eng., 90(10), pp. 1278–1291 (2012).

55

THE MICROSCOPIC STRESS FROM MOLECULAR DYNAMICS SIMULATIONS

Alejandro Torres-Sánchez, Juan M. Vanegas (Sandia Nat. Lab.) and Marino Arroyo

Abstract:

The growing power of modern computers enables the simulation of material and soft-matter systems of increasing size and complexity. However, it is difficult to directly rationalize the raw atomistic trajectories produced by molecular dynamics. Thus, there is a pressing need to upscale molecular dynamics to obtain coarse-grain measures representing the underlying molecular ensembles. Continuum mechanics has been successfully applied to understand the mechanics of a variety of systems at the nanoscale and thus provides a natural framework to interpret molecular simulations of materials.

In particular, computing the microscopic stress field from molecular dynamics is becoming popular to understand the mechanics of different materials including defective crystals, lipid bilayers, membrane proteins, or isolated molecules (see [1,2] and references therein). These computations are usually understood from the classical framework by Irving and Kirkwood [3], which was initially proposed for two-body interactions. However, the definition of the microscopic stress for systems involving multibody potentials remains ambiguous. The major ambiguity comes from the non-unique decomposition of the interatomic forces from multibody potentials into pairwise terms [4]. Different methods to compute the stress from multibody potentials have been proposed [4-7], yet whether these different methodologies lead to stresses satisfying the continuum statements of balance of linear and angular momentum has not been tested.

In this project [1,2]:

We have tested [1] whether the different methods to compute the microscopic

stress in molecular dynamics simulations satisfy the equilibrium equations of

continuum mechanics. Strikingly, we have found that only the stress proposed in

[4] satisfies both balance of linear and angular momentum.

Despite of the success of the procedure in [4] in satisfying balance of linear and

angular momentum, this procedure is not unique and leads to unphysical

stresses for multibody potentials involving more than 4 particles. We have

developed an extension of [4] based on covariance arguments that extends [4] to

arbitrary multibody potentials [2].

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Figure 1: Stress from [4] (A1) and [5] (A2) for a Stone-Wales defect in a graphene sheet. Stress field has been smoothed with a Gaussian kernel to smear out length scales at the interatomic distance. The divergences for each stress (A2 and B2 respectively) show that, while [4] is in equilibrium with a nearly zero divergence, [5] is not. Thus the definition in [4] does not satisfy balance of linear momentum.

References:

[1] A. Torres-Sánchez, J.M. Vanegas, M. Arroyo, under review in Phys. Rev. Lett (2015).

[2] A. Torres-Sánchez, J.M. Vanegas, M. Arroyo, to be submitted to in Phys. Rev. E (2015).

[3] J. H. Irving and J. G. Kirkwood, J. Chem. Phys. 18, 817 (1950). [4] N. C. Admal and E. B. Tadmor, J. Elast. 100, 63 (2010). [5] A. P. Thompson, S. J. Plimpton, and W. Mattson, J. Chem. Phys. 131, 154107

(2009). [6] R. Goetz and R. Lipowsky, J. Chem. Phys. 108, 7397 (1998). [7] H. Heinz, W. Paul, and K. Binder, Phys. Rev. E 72,066704 (2005).

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VIABILITY OF THE PROPER GENERALIZED DECOMPOSITION IN PARAMETERIZED GEOMETRIES FOR FLOW PROBLEMS

A. Huerta1, P. Díez1, S. Zlotnik

Automotive design requires assessing drag and lift coefficients of the vehicle. More precisely, the geometry is modified in order to attain prescribed values of these parameters. This requires evaluating the airflow surrounding the vehicle for each geometrical trial in order to determine the pressure maps on the body and then compute drag and lift. These cycles are both time consuming and require excessive user intervention. They are composed of the following steps:

1. shape modification in CAD geometry, 2. pre-process and determination of computational geometry, 3. flow solver, and 4. post-process.

Moreover, the number of these “expensive” cycles is drastically influenced the accuracy in the evaluation of sensitivities. That is, how variations in the geometrical design parameters modify the outputs of interest (drag and lift).

Following recent contributions of the model reduction approach named Proper Generalized Decomposition (PGD) for parameterized boundaries, see [1,2], the objective is to evaluate the contributions in both, the reduction of a cycle cost, and the reduction of the number of cycles by means of generalized solutions. Of course, this is done keeping, as long-term goal, the utopist paradigm for CFD users of having an instantaneous answer when modifying the parametric geometrical description.

The PGD technique is a possible way towards this ultimate goal. For this purpose a linear incompressible flow model (Stokes flow) will be considered, and a Computational Vademecum [3] will be determined for parameterized shapes of immersed bodies, in order to provide real-time solutions to any user query (each query is characterized by a set of parameters describing the geometry).

Figure 1. Problem statement and GUI for backward facing step.

Figure 1 shows the problem statement and the GUI, to obtain pressure and velocity fields on the fly, for the backward facing step benchmark test. Only one geometrical parameter is considered: the relative step height.

Figure 2 shows the problem statement and the four parameters controlling the shape of an airfoil. While Figure 3 shows a screen capture of the GUI that computes in real-time the velocity and pressure fields around the airfoil.

1 Contact: antonio.huerta@upc.edu or pedro.diez@upc.edu

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Figure 2. NACA airfoil benchmark test.

Figure 2. GUI screen capture for the NACA airfoil benchmark test.

References:

[1] A. Ammar, A. Huerta, F. Chinesta, E. Cueto, A. Leygue, “Parametric solutions involving geometry: a step towards efficient shape optimization”, Comput. Methods Appl. Mech. Eng., 268, pp. 178-193, (2014).

[2] S. Zlotnik, P. Díez, A. Huerta, “Proper Generalized Decomposition of a geometri-cally parameterized heat problem with geophysical applications”, Int J Numer Methods Eng., accepted (2015).

[3] F. Chinesta, A. Leygue, F. Bordeu, J.V. Aguado, E. Cueto, D. González, I. Alfaro, A. Ammar and A. Huerta, “PGD-Based Computational Vademecum for Efficient Design, Optimization and Control”, Arch. Comput. Methods Eng., 20(1), pp. 31-59, (2013).

Free slip

Free slip

t m

c2 [0.5,0.9]

t 2 [0.1,0.25]

m 2 [0.0,0.15]p2 [0.3,0.7]

3

1.6

59

PHD THESES

Validation and generation of curved meshes for high-order unstructured methods Abel Gargallo Facultat de Matemàtica i Estadística Universitat Politècnica de Catalunya 25 July, 2014

Decomposition techniques for computational limit analysis Nima Rabiei ETSE de Camins, Canals i Ports de Barcelona Universitat Politècnica de Catalunya 27 October, 2014

Approximation of phase field models with meshfree methods: exploring biomembrane mechanics Christian Peco ETSE de Camins, Canals i Ports de Barcelona Universitat Politècnica de Catalunya 28 October, 2014

Real-time wave monitoring for elliptic harbor models: An a priori reduced order approach David Modesto ETSE de Camins, Canals i Ports de Barcelona Universitat Politècnica de Catalunya 15 December, 2014

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PUBLICATIONS

A multimesh adaptive scheme for air quality modeling with the finite element method Monforte, L. and Pérez-Foguet, A. International Journal for Numerical Methods in Fluids, Vol. 74, Number: 6, pp. 387-405, 2014

A new continuous-discontinuous damage model: cohesive cracks via an accurate energy-transfer process Tamayo-Mas, E. and Rodríguez-Ferran, A. Theoretical and Applied Fracture Mechanics, Vol. 69, pp. 90-101, 2014

A surface mesh smoothing and untangling method independent of the CAD parameterization Gargallo-Peiró, A.; Roca, X. and Sarrate, J. Computational Mechanics, Vol. 53, Issue 4, pp. 587-609, 2014

Assessment of water resources management in the Ethiopian Central Rift Valley: environmental conservation and poverty reduction Pascual-Ferrer, J., Pérez-Foguet, A., Codony, J., Raventós, E., Candela, L. International Journal of Water Resources Development, Vol. 34, pp. 1741-1759, 2014

Characterization of local wind patterns in complex mountain valleys Pérez-Foguet, A. International Journal of Climatology, Vol. 34, Number: 6, pp. 1741-1759, 2014

Computational evaluation of the flexoelectric effect in dielectric solids Abdollahi, A.; Peco, C.; Millán, D.; Arroyo M.; and Arias I. Journal of Applied Physics, Vol. 116, pp. 093502(1-10), 2014

Error assessment in structural transient dynamics Verdugo, F.; Parés, N.; and Díez, P. Archives of Computational Methods in Engineering, Vol. 21, pp. 59-90, 2014

Esquema adaptativo para problemas tridimensionales de convección-difusión Monforte, L. and Pérez-Foguet, A. Revista Internacional de Métodos Numéricos para Cálculo y Diseño en Ingeniería, Vol. 30, Number: 1, pp. 60-67, 2014

Force Transduction and Lipid Binding in MscL: A Continuum-molecular Approach Vanegas, J. M., and Arroyo, M., PLOS ONE, Vol.9, Num. 12, pp. 1-22, 2014 Forces driving epithelial wound healing Brugués, A.; Anon, E.; Conte, V.; Veldhuis, J.H.; Gupta, M.; Colombelli, J.; Muñoz, J.J.; Brodland, G.W.; Ladoux, B.; and Trepat, X. Nature Physics, Vol. 10, pp. 683-690, 2014

Goal-oriented space-time adaptivity for transient dynamics using a modal description of the adjoint solution Verdugo, F., Parés, N., and Díez, P., Computational Mechanics, Vol. 54, Issue 2, pp. 331-352, 2014

Hybridizable Discontinuous Galerkin with degree adaptivity for the incompressible Navier–Stokes equations Giorgiani G., Fernández-Méndez S., Huerta A. Computers and Fluids, Vol. 98, pp. 196-208, 2014

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Impacts on effluent contaminants from mine sites: Risk assessment, fate, and distribution of pollution at basin scale Yacoub, C., Pérez-Foguet, A., Valderrama, C., and Miralles, N. Environmental Science and Pollution Research, Vol. 21, Number: 9, pp. 5960-5971, 2014

Importance of force decomposition for local stress calculations in biomembrane molecular simulations Vanegas, J.M.;Torres-Sánchez, A.; and Arroyo, M. Journal of Chemical Theory and Computation, Vol. 10, pp. 691-702, 2014

Interplay of packing and flip-flop in local bilayer deformation. How phosphatidylglycerol could rescue mitochondrial function in a cardiolipin- deficient yeast mutant Khalifat, N; Rahimi, M.; Bitbol, A-F; Seigneuret, M.; Fournier, J.-B.; Puff, N.; Arroyo, M.; and Angelova, M. Biophysical Journal, Vol. 107, Issue 4, pp. 879-890, 2014

Nonsingular Isogeometric Boundary Element Method for Stokes Flows in 3D Heltai, L.; Arroyo, M. and DeSimone, A. Computer Methods in Applied Mechanics and Engineering, Vol. 268, pp. 514-539, 2014

On the natural stabilization of convection dominated problems using high order Bubnov–Galerkin finite elements Cai, Q.; Kollmannsberger, S.; Sala-Lardies, E.; Huerta, A. and Rank, E. Computers and Mathematics with Applications, Vol. 66, Issue 12, pp. 2545-2558, 2014

Parametric solutions involving geometry: a step towards efficient shape optimization Ammar, A.; Huerta, A.; Chinesta, F. ; Cueto, E. and Leygue, A. Computer Methods in Applied Mechanics and Engineering, Vol. 268, pp. 178-193, 2014

Phase-field modeling of fracture in linear thin shells Amiri, F.; Millán, D.; Shen, Y.; Rabczuk, T.; and Arroyo, M. Theoretical and Applied Fracture Mechanics, Vol. 69, pp. 102-109, 2014

Shape control of active surfaces inspired by the movement of euglenids Arroyo, M. and DeSimone, A. Journal of the Mechanics and Physics of Solids, Vol. 62, pp. 99-112, 2014

Three-dimensional simulation of crack propagation in ferroelectric polycrystals: effect of combined toughening mechanisms Abdollahi, A. and Arias, I. Acta Materialia, Vol. 65, pp. 106-117, 2014

Understanding and strain-engineering wrinkle networks in supported graphene through simulations Zhang, K. and Arroyo, M. Journal of the Mechanics and Physics of Solids, Vol. 72, pp. 61-74, 2014

Water-sanitation-hygiene mapping: An improved approach for data collection at local level Giné. R., Jiménez, A., and Pérez-Foguet, A. Science of The Total Environment, Vol. 463-464, pp. 700-711, 2014

XLME interpolants, a seamless bridge between XFEM and enriched meshless methods Amiri, F.; Anitescu, C.; Arroyo, M.; Bordas, S.P.A.; and Rabczuk, T. Computational Mechanics, Vol. 53, Issue 1, pp. 45-57, 2014

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CONFERENCE PARTICIPATION

PLENARY

Mechanics of confined solid and fluid thin films: Graphene and lipid bilayers 11th World Congress on Computational Mechanics-WCCMXI, Barcelona (22/7/2014). Semi-plenary lecture “ http://www.wccm-eccm-ecfd2014.org/frontal/ILS.asp Marino Arroyo

Reduced Order Models with (and for) goal-oriented error assessment

11th World Congress on Computational Mechanics-WCCMXI, Barcelona (22/7/2014).

Semi-plenary lecture http://www.wccm-eccm-ecfd2014.org/frontal/ILS.asp Pedro Díez

Réduction de modèles et méthodes avancées pour l’ingénierie numérique Congres NAFEMS FRANCE 2014, Simulation numériique: moteur de performance, Paris , (4 - 5 Juin 2014). Antonio Huerta

KEYNOTES

Unstructured and Semi-Structured Hexahedral Mesh Generation Methods The Ninth International Conference on Engineering Computational Technology Naples, Italy, 2-5 September 2014 J. Sarrate, E. Ruiz-Gironés and X. Roca

INVITED TALKS

Adaptive high-order hybridizable and embedded discontinuous Galerkin International Conference on Spectral and High Order Methods, ICOSAHOM'14, June 23-27 2014, Salt Lake City, Utah, USA, http://www.icosahom2014.org/ Huerta, A., Angeloski, A. and Discacciati, M.,

Adaptive high-order methods for aeroacoustic and flow problems Sixth International Workshop on High-Order Finite Element and Isogeometric Methods., 15th – 18 th July, 2014, Frauenshiemsee Island, Germany Huerta, A., Angeloski, A., Roca, X., Discacciati, M. and Giorgiani, G.,

Key Features of Mesh-free Methods Inspiring Other Approaches Meshfree Methods for Large-Scale Computational Science and Engineering: Theory and Applications of Galerkin and Collocation Methods, Tampa , FlL(USA) October 27-28, 2014 Antonio Huerta,

Mechanics of Supported Graphene: Understanding and Controlling Wrinkles and Bubbles CECAM Workshop on “Graphene’s strain engineering”, Zurich, Switzerland (14/7/2014). http://www.cecam.org/workshop-2-971.html Marino Arroyo

Mechanics of confined solid and fluid thin films: graphene and lipid bilayers Institute of Light and Matter, Lyon (http://ilm.univ-lyon1.fr) (27/5/2014). http://ilm.univ-lyon1.fr/index.php?option=com_cgevents&agentask=3&event=345&lang=2 Marino Arroyo

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RESEARCH SEMINARS

DATE PRESENTER TITLE

25 APR

Behrooz Hashemian LaCàN,

UPC - BarcelonaTech

Introduction to the Mendeley reference manager

9 MAY

Serguei Iakovlev Dalhousie University, Canada

Semi-analytical modeling of shock-structure interactionrecent industry-driven applications

16 MAY

A. Pérez-Foguet LaCaN

UPC - BarcelonaTech

Engineering GD Seminar SeriesFrom one to multi-dimensional poverty metrics. Application to RWSS planning.

10 JUN

Erkan Tuzel Worcester Polytechnic Institute

Massachussets, USA

Transport by populations of fast and slow kinesins uncovers novel family-dependent motor characteristics important for in vivo function

25 JUL

Abel Gargallo Peiró LaCaN

UPC - BarcelonaTech

Generation of curved meshes for high-order unstructured methods

19 SEP

Enrique Nadal Soriano École Centrale de Nantes, France

Fractional Derivatives And Applications

27 OCT

Nima Rabiei LaCaN

UPC - BarcelonaTech

Decomposition techniques for computational limit analysis

27 OCT

Hector Gomez Universdad d’A Coruña, Spain

Isogeometric AnalysisAn overview of the technology, comparison with the finite element method and application to phase-field modeling.

28 OCT

Christian Peco Regales LaCaN

UPC - BarcelonaTech

Approximation of phase-field models with meshfree methodsexploring biomembrane dynamics

31 OCT

Ceren GURKAN LaCaN

UPC - BarcelonaTech

eXtended Hybridized Discontinuous Galerkin (X-HDG) Method

16 DEC

Raquel García LaCaN

UPC - BarcelonaTech

A LATIN Solver for the Electric Grids Power Flow problem

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OUTREACH

ORGANIZATION OF MEETINGS & EVENTS

Joint organization of 11th World Congress on Computational Mechanics (WCCM XI), 5th European Conference on Computational Mechanics (ECCM V) and 6th European Conference on Computational Fluid Dynamics (ECFD VI). Antonio Huerta (Co-Cahirman), Pedro Díez (Organizing Committe), Irene Arías and Antonio Rodríguez-Ferran (Local Organizing Committe)

COMMITTEES

Participation in external PhD Theses Committees

Antonio Huerta

Mohamed Nazeer Shahul Hameed, "PGD framedwork for Domain Decomposition Methods", Ecole Centrale de Nantes, France, March 19, 2014

Pedro Díez:

Enrique Nadal, “Cartesian grid FEM (cgFEM): High performance h-adaptive FE analysis with efficient error control. Application to structural shape optimization”, Universitat Politècnica de València, January 28, 2014

Franco Dassi, “Advanced Techniques for the Generation and the Adaptation of Complex Surface Meshes”, POLITECNICO DI MILANO, September 17, 2014

M. Jérémy Veysset, “Anisotropic mesh adaptation and stabilized finite elements method for solving conjugate heat transfers and turbulent flows”, MINES ParisTech, Centre de Mise Forme des Matériaux (CEMEF), France, September 29, 2014

Marino Arroyo

Miquel López-Suárez, “Non-linear nanoelectromechanical systems for energy harvesting”, Universitat Autònoma de Barcelona, April 30, 2014

Guillermo Rodriguez-Lazaro, “Red Blood Cell mechanics: from membrane elasticity to blood rheology”, Universitat de Barcelona, June 30, 2014

Other academic evaluation committees:

Antonio Huerta

Member of Experts Panel for the Consolidator Grant 2014 Evaluation, European Research Council

Membre externe du Comité de sélection pour le recrutement d'un Maître de conférences de "Mécanique" pour le département de Génie Mécanique, poste n° 60 PR 0143., NS Cachan, Dpt Génie Mécanique / LMT Cachan, France

Membre du Directoire du LabEx Tec 21, (Advisory Board), Laboratoire des Ecoulements Géophysiques et Industriels, BP 53, 38041, Grenoble cedex 9, France

Membre de Commission des Sciences Exactes et Naturelles – 3 (SEN-3), Fonds de la Recherche Scientifique – FNRS, 5 rue d'Egmont, B - 1000 Bruxelles

Judge for the Robert J. Melosh Competition for “The best student paper in finite element analysis”, April 25, 2014, Duke University (North Carolina, USA)

65

Pedro Díez:

Member of the HDR committe for Dr. -

à diriger des recherches, l’Institut National des

EXTERNAL SEMINARS, COURSES

Courses and seminars delivered by LaCàN members

Antonio Huerta:

“Discontinuous Galerkin methods and reduced order models. The scope ranges from mathematical background to applications”. Short course in Advanced Finite Element Technologies, International Centre for Mechanical Sciences (CSIM), Udine, Italy, October 6, 2014 — October 10, 2014

Marino Arroyo

Guest Lecturer, PhD Course on “Nonlinear continuum mechanics" at Politecnico di Milano (10/2014).

Invited Seminars:

“Mechanics of supported material interfaces: graphene and epithelial tissues”, Politecnico di Milano (10/2014).

"Mechanics of confined solid and fluid thin films: graphene and lipid bilayers”, Institute of Light and Matter, Lyon (5/2014).

PRESENCE IN MEDIA

Videos in Youtube

Pedro Díez, "Reduced Order Models with (and for) goal-oriented...", WCCM XI-ECCM V-ECFD VI, 2014

https://www.youtube.com/watch?v=HOeWDPBhPC4

Francesc Verdugo, "Error assessment and adaptivity for structural..." | WCCM XI -ECCM V-ECFD VI, 2014

https://youtu.be/keDbfgZZWGg

Newsletters

ECCOMAS Newsletter July 2014, Pedro Díez (editor) http://www.eccomas.org/vnews/1/22/6

IACM expressions # 34, January 2014, Antonio Huerta (Secretary General) http://iacm.info/vpage/1/0/IACM-Expressions/34

IACM expressions # 35, June 2014, Antonio Huerta (Secretary General) http://www.iacm.info/cvdata/cntr1/dtos/img/mdia/Expressions-35.pdf

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Press notes WCCM 2014

“Barcelona será a partir de mañana la capital mundial de los métodos numéricos”, EFE, July 20, 2014

http://www.abc.es/agencias/noticia.asp?noticia=1627712

“¡Hay mecánica computacional detrás de una patata frita!”, Pelayo Herrera, Andrea . El Mundo, july 25, 2014,

http://www.elmundo.es/economia/2014/07/25/53d122ba268e3e0e168b45a0.html

“Barcelona is hosting the world's most important conference on computational mechanics and numerical methods”, Catalna News Agency, July 23, 2014

http://www.catalannewsagency.com/business/item/barcelona-is-hosting-the-world-s-most-important-conference-on-computational-mechanics-and-numerical-methods

“La cirurgia robotitzada, àrea d’investigació en auge en el camp de la mecànica computacional”, R. Romero / A. Calvo, Barcelona Televisió, July, 21, 2014

http://www.btv.cat/btvnoticies/2014/07/21/cirurgia-robotitzada-congres-mecanica-computacional/#None

“El Congreso Mundial de Mecánica Computacional reúne a 4.000 expertos en simulación”, Agencia EFE, July 21, 2014

http://newscaster.ikuna.com/53_cataluna/2636242_el-congreso-mundial-de-mecanica-computacional-reune-a-4-000-expertos-en-simulacion.html

http://www.lavanguardia.com/vida/20140721/54412094832/congreso-mundial-mecanica-computacional-reune-a-4-000-expertos-en-simulacion.html

http://bit.ly/1JvvyDs

http://ecodiario.eleconomista.es/interstitial/volver/50023286782/ciencia/noticias/5957234/07/14/El-Congreso-Mundial-de-Mecanica-Computacional-reune-a-4000-expertos-en-simulacion.html#.Kku8M2Yy7bumDdJ

http://noticias.lainformacion.com/salud/investigacion-medica/congreso-mundial-mecanica-computacional-reune-a-4-000-expertos-en-simulacion_MzdD5xRe3V8BcESjlDDMK4/

http://eldia.es/2014-07-21/sociedad/2-cientificos-exponen-nuevos-avances-informaticos.htm

http://noticias.terra.es/ciencia/congreso-mundial-mecanica-computacional-reune-a-4000-expertos-en-simulacion,c86a9e6043957410VgnCLD200000b1bf46d0RCRD.html

http://www.radiointereconomia.com/2014/07/21/congreso-mundial-mecanica-computacional-reune-a-4-000-expertos-en-simulacion/

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RESEARCH STAYS

Pedro Díez:

Visiting Professor, ENS Cachan (France), May 2014

Invited Researcher, Ecole Centrale Paris, April 2014

Invited Professor Politecnico di Milano, March 2014

Antonio Huerta

Visiting Professor, Swansea University (UK), February 2014

Visiting Professor Ecole Centrale Nantes, March 2014

Visiting Professor, Swansea University (UK), June 2014

Visiting Professor Ecole Centrale Nantes, December 2014

EQUIPMENT & FACILITIES

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The Laboratori de Càlcul Numeric offers high-quality computational facilities to fulfill its research and educational mission.

On one hand a computer room equipped with a 14 workstations is available for researchers and students. On the other hand, a Beowulf cluster for high-performance computing is also available for LaCàN members. It is composed by 46 nodes dedicated to distributed memory applications (16 acquired in 2009 and 30 acquired in 2010) and one master node. In addition, during this year we have acquired a node equipped with 768GB of RAM memory and four octa-core processors for shared memory applications. All nodes are connected using an Infiniband network.

TRAINING

75

Coordination of graduate programs.

LaCàN is involved in the coordination of educational and training programs. In particular, professors from LaCàN are responsible of the coordination of two prestigious programs awarded with the Erasmus Mundus distinction by the European Commission:

The Master of Science in Computational Mechanics started in the academic year 2007-2008 (http://www.cimne.com/cm-master/) coordinated by UPC and having as partners: University of Swansea, l’École Centrale de Nantes and University of Stuttgart. The Erasmus Mundus grant was renewed in 2012 (for five years more). In this new phase we introduced some modifications to the program and we incorporated as full partner Tsinghua University (Beijing, China). Tsinghua is acting as “third country” partner (according to the EC jargon) and therefore their role is not the same as for the European partners, they mainly host students for co-supervised Master Theses.

The Erasmus Mundus Joint Doctorate SEED (Simulation in Engineering and Entrepreneurship Development; http://www.cimne.com/emjd-seed/). Is also coordinated by UPC and participated by seven other European institutions from different EU countries (Université Libre de Brusseles from Belgium, Ecole Centrale de Nantes from France, Technische Universität München from Germany, Università degli Studi di Pavia from Italy, Istituto Superior Técnico from Portugal, Technische Universiteit Eindhoven from The Nederlands and Swansea University from UK).

Both programs are coordinated by UPC, School of Civil Engineering (Escola de Camins) and managed by CIMNE.

Participation in training programs

Civil Engineering School PhD in Simulation in Engineering and Entrepreneurship Development (SEED) PhD in Civil Engineering Master of Science in Computational Mechanics Master en Ingeniería de Caminos, Canales y Puertos (Civil Engineering, Professional Engineer) Master in Geological and Mining Engineering

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Master in Construction Engineering Bachelor in Civil Engineering Bachelor in Construction Engineering Bachelor in Geological Engineering (joint degree UPC - Universitat de Barcelona) Faculty of Mathematics and Statistics PhD in Applied Mathematics Master in Advanced Mathematics and Mathematical Engineering Bachelor in Mathematics Barcelona College of Industrial Engineering Bachelor in Biomedical Engineering Bachelor in Chemical Engineering Bachelor in Electrical Engineering Bachelor in Energy Engineering Bachelor in Industrial Electronics and Automatic Control Bachelor in Mechanical Engineering Castelldefels School of Telecommunications and Aerospace Engineering Master in Aerospace Science and Technology Bachelor in Air Navigation Engineering Bachelor in Airports Engineering

77

FINANCIAL REPORT

79

2014 Income

TOTAL FUNDING FUNDING

2014

2014 SGR 01471 – Mètodes numèrics en ciències aplicades i enginyeria

GenCat 48 880,00 € 9 776,00€

Direcció Pla de Doctorats Industrials GenCat GenCat 36 000,00 € 12 000,00€

Desarrollo y analisis del metodo PGD para procesos de conformado termoplástico

DPI2011-27778-C02-02 MICINN

147 620,00 € 40 115,94€

Modelos de campo de fase para problemas de discontinuidad libre: métodos computacionales y aplicaciones en fractura, materiales ferroelectricos y membranas biologicas

DPI2011-26589 MICINN

180 290,00 € 60 096,66€

Modelos computacionales para dinámica multicelular: aplicación a embriogénesis y movilidad celular en tejidos"

DPI2013-43727-R

48 400,00 € 16 133,33 €

Desarrollo y analisis de formulaciones hdg para problemas heterogeneos en dinamica de fluidos computacional

MTM2013-46313-R

35 090,00 € 11 696,66 €

KIC-Offshore Test Station EIT-KIC 171 862,00€ 57 287,54 €

Predictive models and simulations in nano- and biomolecular mechanics: A multiscale approach (PREDMODSIM)

ERC ST.G 1 462 198,00€ 292 439,60 €

Computer methods to predict three-dimensional hydraulic fracture networks

Marie Curie ERG

100 000,00 € 25 000,00 €

Virtual control methods for coupling heterogeneous problems

Marie Curie ERG

100 000,00 € 25 000,00 €

Simulador numérico composicional para yacimientos naturalmente fracturados vugulares con comportamiento fractal (PETROSOFT)

CONACYT 185 000,00 € 61 666,66 €

Industrial PhD in collaboration with SEAT 29 100,00 € 9 700,00 €

TOTAL 2.544.440,00 € 620.042,60 €

Income (per source cathegory)

Expenditure

Competitive Grants EU 399 727,14 € Personnel 315 103,00 €

Competitive Grants ES 128 042,60 € Equipment 7 534,98 €

Competitive Grants CAT 31 476,00 € Travel 48 583,44 €

Private Research Funding 61 666,66 € Others 17 224,38 €

Overhead 73 324,15 €

Total income 620 042,60 € Total expenditure 461 769,95 €

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Competitive Grants EU

64%

Competitive Grants ES

21%

Competitive Grants CAT 5%

Private Research Funding

10%

INCOME

EXPENDITURE

Personnel 68.24%

Equipment 1,63%

Travel 10,52%

Others 3,73%

Overhead 15,88%

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ENQUIRIES AND FURTHER INFORMATION

Prof. Antonio Huerta Director Prof. Pedro Díez Deputy Director

Laboratori de Calcul Numeric - LaCàN Dept. Matematica Aplicada III, ETS de Ingenieros de Caminos UPC-Barcelona Tech T: + 34 401 79 59

antonio.huerta@upc.es http://www-lacan.upc.es/huerta/ pedro.diez@upc.edu http://www-lacan.upc.es/diez