Architecture: CFD Simulation Applications Using scSTREAM · Conventional CFD (Unstructured Mesh)...

｜1© Cradle North America

June 2016

Cradle North America

Architecture: CFD Simulation Applications Using scSTREAM

WHAT IS CFD?

It is the numerical simulation methods to simulate fluid

dynamic phenomena by solving governing equations of

fluid, heat, diffusive species, and/or chemical reactions.

CFD (Computational Fluid Dynamics)

Physics / Mathematics / Computer Science / Visualization Techniques

Thermo-Fluid Analysis

What is CFD?

What is scSTREAM?

• Fluid Dynamics, Heat Transfer, & Daylight Analysis Software

scSTREAM Released in 1984

Realization of Architectural and Electrical Effectiveness

Development Focused on Speed, Accuracy,

and usability

Implementation of Architectural Specific Functions

History

Examples

Indoor Applications

Examples

Indoor Applications – Human Comfort

Examples

Indoor Applications – Data Centers

Examples

Indoor Applications – Humidity Control

Examples

Indoor Applications – Air Quality

Examples

Outdoor Applications

Examples

Outdoor Applications – Large Scale

Examples

Outdoor Applications – Site Analysis

Examples

Outdoor Applications – Diffusion Analysis

Examples

Outdoor Applications – Site Thermal Analysis

Examples

Natural Ventilation

Examples

Natural Ventilation- Natural Convection

Examples

Natural Ventilation – Ventilation Prediction

Examples

Natural Ventilation – Energy Savings

Examples

Natural Ventilation – Sustainable Designs

Examples

Other Applications

Examples

Other Applications – Daylight and Illuminance

Examples

Other Applications – Hydraulic Analysis

Examples

Other Applications – Renewable Energy

Compressible / Incompressible fluid

Newtonian / Non-Newtonian fluid

Heat radiation / Solar radiation

Multi-phase / Free surface / Particle tracking

Humidity / Condensation /Solidification / Melting

Diffusion / Chemical reaction / Combustion

Porous media / Canopy Model

Fan models / A/C model / Anemostat model

Thermal conduction panel / Peltier & heatpipe

Thermal circuit model (2/3/multi resistors, DELPHI)

8 Turbulence models / LES

Static Magnetic Effect

Ventilation efficiency evaluation, age of air index

Conjugated heat transfer, Joule heating

Multi-purpose CFDStructured Mesh

Introduction to scSTREAM

scSTREAM is a Multi-purpose CFD software developed not only for CFD experts but also for design engineers in all industries.

Ease of use

Accuracy

Low memory consumption

Stability

Concept

Introduction to scSTREAM

Physical Models

Multi-purpose CFDStructured Mesh

｜27© Cradle North America Last updated: April 2016

Solver

Friendly User interface

Rapid and Easy Meshing

Outstanding Computational speed and stability

Low Memory Consumption

Features of scSTREAM

IDFIDF 2.0 & 3.0

GerberZuken CR5000/Board Designer

RS274D & RS274XCadence ALLEGRO

RZ274X

CSV BMP

Architecture design

Revit *ArchiCAD *

Friendly User interface (CAD Importation)

CATIAv4&v5PRO/E,CreoSolidWorksNXSolidEdgeParasolid

STEPACIS(SAT)VDAFSIGESDXFSTL

XGLNASTRANSHAPE

Revit scSTREAM(STpre)

Revit2STREAM and ArchiCAD2STREAM are add-in modules to Revitand ArchiCAD.

2 modes for geometry handling

– Detailed model

– Simplified model

Assembly structure is maintained

Automatically detect the attributes of a part and simply the model for CFD

Friendly User interface (Revit Import Tool)

Simplification function

– Walls and floors are converted to sketch parts. Doors and windows are converted to cutout parts. Other parts are obtained as polygon.

Simplified Not simplified

Friendly User interface (Revit Import Tool)

Import Map Data

ParasolidSTEPSHAPE(GIS)

Autodesk(R) Revit(R) Architecture*GRAPHISOFT ArchiCAD*

CATIAProE

Solidworks(and more)

KOKUSAI KOGYO CO., LTD.

Sora Technology Corporation

*Option(Direct Interface)

Friendly User interface (GIS Data Import)

Terrain

Buildings

Simulate

Collect Map Data Import Into scSTREAM

Friendly User interface (GIS Data Import)

(3D building model data)

( 3D topography data)

(GIS Data Import)

Number of Mesh: 2,800,000Calculation time: 55minComputer spec: Pentium 4, 2.8GHz

(GIS Data Import)

X_T File

（Model Data）CSV Mapping Tool

（Property）

Merged!

Material

properties

Heat source

Emissivity

Initial Temp

Etc…

Setting material property at once using CSV（Excel）file

This function makes

setting properties for

hundreds of parts easy

Friendly User interface (CSV)

Basic boundary condition setting templates.

External Flow (through Buildings)Multiple Default Templates

Friendly User interface (Condition Wizzard)

Custom built library registration

Drag & drop to reuse a part from

a library

Friendly User interface

2D DXF Files Extrusion

Friendly User interface (Loading 2D DXF Files)

<1 sec. for 1,473,171 mesh<10 sec. for 10 million mesh

5 to 10 times faster than conventional CFD (unstructured) software

Windows XP x64 edition

4GB memory

Intel Xeon X5680 (3.33GHz)

Rapid and Easy Meshing

scSTREAMConventional CFD

(Unstructured Mesh)

Data Cleaning None 2 to 3 daysdepending on the software

Mesh Generation >1 min. 2 to 5 hours

Calculation 1 day 5 days

Total 1+ day 7 to 8 days

Intel Xeon E5-2687W 3.10GHz

This process is likely to be repeated a

couple of times

Outstanding Computational speed and stability

scSTREAMConventional CFD

(Unstructured Mesh)

Data Cleaning None 2 to 3 daysdepending on the software

Mesh Generation >1 min. 2 to 5 hours

Calculation 1 day 5 days

Total 1+ day 7 to 8 days

Intel Xeon E5-2687W 3.10GHz

X 33 days vs. 3-4 weeks+

Low Memory ConsumptionOutstanding Computational speed and stability

6 million elements per 2GB50 mil. elements/16GB100 mil. Elements/32GB

# of mesh

Comparison of the # of mesh per 2GB RAM memory

40 to 100 million elements

Low Memory Consumption

FUNCTIONS FOR ARCHITECTURE AND BUILDING

Cartesian CoordinateCylindrical coordinates Multi-block meshingArbitrary shape meshTransient / Steady stateIncompressible/Compressible Conjugate heat transferNon-Newtonian/NewtonianThermal conduction panel Moving object Various Fan models8 Turb. ModelsLESParallel computing (MPI)UDF

RadiationSolar radiationParticle trackingHumidityDiffusionCondensation/SolidificationFree SurfaceMeltingChemical reactionCombustionPorous media

Grass establishment /Canopy ModelDiffuser ModelsA/C modelMoisture absorbentVentilation efficiency indicesWind Index toolStatic Magnetic Effect

Joule HeatingPeltierHeatpipeGerber data ImportThermal circuit models

Overview of Functions

Round-shape Angular-shape

※Handbook of Heating, Air-Conditioning and Sanitary Engineering, 13th Edition 2, p.578 (in Japanese only)

Flow from an Anemostat varies depending on operation types.

Horizontal/Vertical flows

Cooling/Horizontal flow

Heating/Vertical flow

Anemostat Model

Anemostat model with radial outlet placed in a large space can be simplified for less

calculation load.

Evaluation on detailed local flow near anemostat is not available with this model. For cooling analysis, anemostat model must be divided as given above for inflow calculation accuracy.

Direction & distribution of inflow from anemostat inlet vary with

model shape & operation mode.

Detailed analysis requires enormous amount of mesh

Modeling enables calculation with less mesh amount & calculation load

Simplified condition set-up Not pursued accuracy

(physical phenomenon is ignored)

*Excerpt from the case presented by Shinryo Corporation at the 15th Cradle Users Conference (October 2005)

*Handbook of Heating, Air-Conditioning and Sanitary Engineering, 13th Edition 2, p.578

*Modeling method by Shinryo Corporation.

Round shape

Flow direction:Cooling- HorizontalHeating- Vertical

Required mesh division number during cooling analysis:4 elements (2x2x1) 9 elements (3x3x1)

Angular shape

Anemostat model

Angular shapeRound shape

Anemostat Model

A new air conditioner part, linear diffuser model, has been implemented.

The linear diffuser model can be used as a supply air opening of an air conditioner unit (flow rate).

HVAC Linear Diffuser Model

Dew condensation & evaporation in a bathroom

Humidity, dew condensation and evaporation

Functions: Humidity Analysis

Smoke diffusion from two chimneys with different conditions

Fixed velocity1.0[m/s]

Chimney ＨSmoke qty.3[l/s]

Chimney LSmoke qty.1[l/s]

Fixed static pressure 0.0[m/s]

Diffusion

Functions: Diffusion Analysis

Velocity vector Marker particle & temperature contour

Mass particle & temperature contour with turbulent diffusion

Particle tracking of jet flow

Not only to visualize unsteady flow, but to simulate particle-flow interaction.

Maker particle

Mass particle

Particle motions diffusion affect

Functions: Particle Tracking Function

｜53© Cradle North America53

Particle analysis with reaction

Simulation of spray cooling

Cooling by evaporation of sprayed liquid.

Movements of liquid drops are expressed by

particles.

Analysis of particle tracking with reaction can be calculated

Functions: Particle Analysis

VOF method MARS method

Change in surface by capillary action

Face Opening ratio: 0

Initial water level

Shape recognition by VOF method

In VOF methodInitial shape

Simulate surface motions of fluid by influences of gravity and surface tension

– VOF method：solves a single fluid in scSTREAM.

– MARS method：determines surface geometry based on the volume fraction of fluid (VOF). Solves 2 different fluids simultaneously.

Free surface

VOF method – Accurately calculates the fluid volume fraction in

computation grids.

– Difficult to capture a precise interface between fluids due to lack of information about interface shape.

Functions: Multiphase Flow Analysis

Only one out of two phases to be solved: To ignore unnecessary phase to be solved in order to keep analysis region minimum

To set larger time interval

Single phase MARS method (Liquid phase only)

Water gate with a dam

– Precise volume conservation

– Precise shape conservation

– Continued volume fraction of fluid on computational element surfaces

– Combination analysis with particle tracking method for dispersed objects & smaller than mesh size (e.g. bubbles or droplets)

– Coupling analysis with arbitrary shaped object by using stationary VOS model

– Single fluid simulation is available

– Single phase: less computational load and calculation time

– Advantage of MARS method: precise conservations of volume fraction & shape

For transient analysis only.

Setting VOF value of inflow fluid for Inlet condition.

During solving pressure equation, setting number

smaller than default (1000) for matrix iteration

may be a cause of divergent or failure to get the

right pressure.

MARS method

Functions: Multiphase Flow Analysis

Calculate scales of ventilation efficiency to find the effective ventilation condition

Evaluation of ventilation efficiency in a room

Inlet (air supply)

Outlet

Lifetime

of air

OutletOutlet

Inlet 1

Inlet contribution rate of Inlet 1

index to see how good specific Inlet / Outlet contributes at specific region when existing multiple ventilation openings.

Index for age of air

Scales for ventilation efficiency by solving diffusion

– Normalized concentration in occupied zone: Mean concentration of contaminants in a specified region. Smaller value indicates better ventilation.

– Index for age of air: Time taken for supplied air from inlet to reach a particular point.

– Index for residual life time of air：Time taken for air to reach from a particular point to outlet

– Inlet contribution ratio:

– Outlet contribution ratio:

ual lifetim

e of air

Evaluation of ventilation efficiency

Functions: Ventilation Efficiency Analysis

Air conditioner is regarded as circulatory flow.

Enhanced Ventilation Efficiency Index

OFF ON

Supply air openingReturn air opening

Age of Air increases due to circulatory flow.

Index of age of air

Large index for age of air= Low ventilation efficiency

Circling airflow

= Not ventilated well

Streamlines:

Small index for age of air

= High ventilation efficiency

No circling airflow= Ventilated well

P-Q characteristics that is applied to boundary condition of fan simplifies the calculation of flow. Different flow patterns by rotation effect can be considered.

解析結果

P-Q characteristics represent fan capacity; relationship between pressure difference

across a fan & mass flow rate

Computation time: 23 min.

Centrifugal flow

22 min.

Axial FlowMixed flow(radial & axial)

30 min.

*Steady state analysis*Number of mesh: 430,272*Machine spec: Pentium4 2GHz

Flow volume [Less] [More]

Streamline plots by flow rate differences

Centrifugal-effect fan model

Functions: Fan Model

Calculate assessment index of wind environment based on Murakami Index by setting conditions in scSTREAM through VB interface operation.

The source code of VBScript is disclosed. No modified or edited source code is supported under Cradle’s support service.

Sttools function

[Tools]-[WindTool]

3. Calculate assessment index.

1. Create a CAB file containing building information data. Wind flux condition is not necessary.

2. Set analysis domain. Set wind conditions in 16 directions.Execute solver.

4. Visualize and check a result with index.

WindTool: assessment tool for wind environment

Functions: Assessment of Wind Environment

Sttools function

Murakami Index：

Based on occurrence frequency of strong wind.

Exceedance frequency of daily maximum instantaneous wind

velocity is calculated on 3 scales. The assessed rank of wind

environment is determined from 3 stages by the result.

Sttools function

1. Create a CAB file containing building information data. 2. Set wind conditions in 16 directions.

Execute solver.3. Calculate assessment index.4. visualize and check a result

with index.

Murakami Index: One of wind environment assessment indices with the consideration of 16 wind directions, probabilities of wind direction and wind strength

Sttools function

Enables users to run simulations with varied conditions which is unavailable in scSTREAM standard set-ups.

Inlet: slits

Outlet: fanHeat source (copper)

Heat value: UDF

Simulation of a heat source depends on ambient temperature

2.4 2.5 2.6 2.7 2.8 2.9 3 3.1 3.2

Log (absolute temp.)

Heat value(W/m3)

[mil.]

Log(Absolute temp.)

Heat value(w/m3)

2.4362 1.0X105

2.5092 2.0X105

2.6749 2.5X105

3.1048 2.7X105

Temperature-dependent heat value[Source Condition]-[Volumetric Source Condition] tab-[Volumetric heat source] dialog -check [User-Defined Function] & click [Details] -register the following UDF;

a=TEMP+[273.0]

b=log(a)

Result=tbl(@T:<table name>,b)

Velocity Temperature

User-defined functions (UDF)

Functions: User-Defined Functions

Customize to run calculations in the background of Office products

Benefits

Interface to the Office environment:

allowing users minimum-setting operations in the familiar Office environment to them

Automation of operation procedures:

reducing time- & effort-consuming operations such as minor geometry changes and mass calculations in different condition

Flexible customization at users’ convenience:

enabling users to build operation system depending on analysis objects and conditions

Set parameters in the Excel file

Create geometry to visualizing results with automated operations in the

background

A simulation result is output on the Excel file

*VBA: Microsoft’s event-driven programming language to enhance functions of Office products.*VBS: Microsoft’s active scripting language used in Microsoft Windows and Internet Information Server.

Customized automation with VBA* & VBS*

Internet Explorer

Microsoft Excel

Functions: VB Interface

TemperatureAbsolute humidity

Outdoor Indoor

32 ℃90%RH

25 ℃10%RH

Hot & Humid

Absorption and desorption of moisture by humidity control material such as stucco can be simulated with the consideration of ; absorption/desorption of moisture moisture conductivity latent heat of vaporization(interaction between moisture and heat)

Functions: Humidity Transfer in Solids

Cut cell method approximates a curved surface using polyhedrons.

– If the resolution is improved, the standard staircase approximation can be used.

If mesh resolution is sufficient

Functions: Cut Cell Meshing Method

Problems with staircase approximation (part 1)

– Does resistance occur even when freeslipconditions are set for walls?

A horseshoe-shaped rectangular duct is analyzed.

When freeslip conditions are set for the walls and no separation occurs in the passage, the pressure difference between the inlet and outlet should be zero!

※ From Function example 23-1

Pressure [Pa] Pressure [Pa]

With staircase approximation, poor accuracy of part shape causes high pressure loss.

Pressure distribution for cut cell method

※ Criteria parameter of cutcell method is set to 0.01.

ΔP=0.98 [Pa] ΔP=0.0088 [Pa]

Pressure increases due to flow impinging

on solid wall

Pressure drops due to rapid

change of flow direction

Pressure distribution forstaircase approximation

Can be used for accurate representation of curved geometry.

– If the resolution is improved, the standard staircase approximation can be used.

Finite Element Model using hexa or tetra

elements on top of Cartesian grids

Functions: Finite Element Modeling

Solar radiation effects is considered as a heat source term in the energy equation, after specifying locations where the radiation affects.

Indoor temperature change by solar radiation( 10 am to 3 pm)

PartitionWindowTransmittance:100%

Temperature distribution

All fluid is set as 100% transmission. Influence on other objects by reflected solar radiation is neglected.

10：05 am

12：30 pm 3：00 pm(Transient analysis, 5 hours)

Solve temperature distribution considering influence of solar radiation.

Solar radiation

Functions: Solar Radiation Analysis

Insolation of each part

Direct solar radiation

e.g., Insolation (14:30p.m.)

Table: Corresponding relationship between part

number and name

Part# P/N

1 Partition

2 Outer wall_Xmax

3 Outer wall_Ymax

4 Outer wall_Xmin

5 Outer wall_Ymin

6 Inner wall_Xmax

7 Inner wall_Ymax

8 Floor

9 Inner ceiling

10 Inner wall_Xmin

11 Inner wall_Ymin

Outer wall_Xmin

WindowA

WindowB

Inner wall_Xmin

PartitionOuter wall_Ymin

Outer wall_Xmax

Inner wall_Ymax

Outer wall_Ymax

Consideration of sky solar radiation enables the user to treat the rigorous reflection.

Direct solar radiation (Diffused reflection is considered) + Sky solar radiation

Contour map of surface temperature(Transient analysis)[30 min]

Insolation (W/m2)0

1 2 3 4 5 6 7 8 9 10 11

Insola

Part number

Reflectance of the ground surface of sky solar radiation

Insolation of sky solar radiation

Diffuse reflectance of direct solar radiation

Insolation of direct solar radiation

Flow, heat, and solar radiation with/without considering the effect of sky solar radiation are analyzed by using the solar radiation function.

Obtains temperature distribution considering the effect of sky solar radiation as well as direct solar radiation.Sky solar radiation = Solar radiation that reaches to the ground after being diffused and reflected by dust and water vapor in the atmosphere.

Sky solar radiation

Functions: Sky Solar Radiation

• 2013 ASHRAE Handbook Sampling locations

• (Globally) 5384 locations

(In Japan) 190 locations

Equations for solar radiation:

(Note) Locations with complete annual data are

selected as the sampling locations

6364.1

h07995.650572.0)hsin(

357.0007.0852.0202.0d

204.0151.0043.0219.1b

Daily variation

by ASHRAE][ ;

altitudeSolarh

massAirm

locationondependentdepthopticalDiffuse

locationondependentdepthopticalBeam

WmirradiancehorizontaldiffuseskyClearE

WmirradiancenormalbeamskyClearE

WmfluxradiantstrialExtraterreE

Functions: Solar Radiation Based on ASHRAE Data

Example: Solar radiation calculation in Hawaii

Leaves

TrunkRoof

Condition region:

porous media

Solar radiation

Trunk & Leaves

Fixed temperature: 25℃

(Note)

The trunk absorbs water and the

leaves release water vapor by

photosynthesis. In other words, the

trunk and leaves combine to keep

the temperature constant.

Wind: ( 0.5 , 1.0 , 0.0 ) m/s13 m

MaterialTrans-

missivityAbsorp-tance

Sand 0 0.3

Road 0 0.4

Roof & Poles 0 0.1

Seat 0 0.3

Trunk 0 0.5

Leaves 0.3 0.7

(Note) Transmissivity is set to leaves.

Grouping for sky solar radiation Flow direction

09:00 12:00

15:00 18:00

Solar radiation heat fluxes

09:00 12:00

15:00 18:00

Surface Temperature(C) Surface Temperature(C)

Surface Temperature(C)Surface Temperature(C)

Surface temperatures

Setting of light sources

Specifying a probe face

– Set an arbitrary virtual face in space to output illuminance.

– The face does not affect the analysis result. Its view factor is calculated.

– The face can also be used to calculate the amount of heat from solar radiation (SUNS) and mean radiant temperature (MRT)

Lighting

* The ceiling is intentionally hidden.Ceiling light

Spotlight

Illuminance at a probe face (height: 1 m)

Only the spotlight is on. All the lights are on.Analysis example

Functions: Illuminance Analysis

Addition of output variables for illuminance analysis (FOUT_LUMI command)

LMCE: Luminance DA: Daylight autonomy

ILLP: Illuminance of lighting sources cDA: Continuous daylight autonomy

DF: Daylight factor UDI: Useful daylight illuminance(Note) All the variables can be output for probe faces.

For details on the variables, refer to User's Guide Basics of CFD Analysis 2.2.3 Solar radiation (7) Output variables of daylight simulation.

Contour map of DFContour map of ILLP

Functions: Illuminance Analysis

THANK YOU FOR YOUR ATTENTION!

QUESTIONS?

COOK@CRADLE-CFD.COM

Architecture: CFD Simulation Applications Using scSTREAM · Conventional CFD (Unstructured Mesh)...

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