ANSA-TGrid: A Common Platform for Automotive CFD Preprocessing · ANSA-TGrid: A Common Platform for...
Transcript of ANSA-TGrid: A Common Platform for Automotive CFD Preprocessing · ANSA-TGrid: A Common Platform for...
ANSA-TGrid: A Common Platform for Automotive CFD Preprocessing
Xingshi Wang, PhD, ANSYS Inc. Mohammad “Peyman” Davoudabadi, PhD, ANSYS Inc.
Overview
Motivation Advantages Use Case I: External Aero Dynamic Simulation Use Case II: Vehicle Thermal Management Simulation
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Motivation Conventional vs. Integrated Approach
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Topo Level: Manual, Time consuming Traditional approach requires users to
manually remove gaps, resolve overlaps and intersections for ALL components in the model.
In the conventional approach, user has to somehow manually create cap and contact faces to patch leakages and preserve conduction paths.
Mesh Level: Semi-automated, More efficient
Leverage wrapping technology as much as possible with minimum manual efforts. Wrap surface is leakage free.
Invest manual efforts only to create high fidelity surface mesh and preserve conduction path between different materials.
Resolve connection on the mesh level is more efficient and flexible.
To create a leakage free, conformal mesh and ensure physical conduction paths, all the overlapping, intersecting, and gap regions have to be fixed and connected.
ANSA-TGrid Interface
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Part Manager
ANSA-TGrid Tool Tab
ANSA-TGrid Function List
World Car Courtesy of PTC
Highly automated; maximizes the outcome of engineering time
Extensive control of mesh quality suitable to all automotive simulations
Parallel execution Flexible and heterogeneous inputs (CAD,
existing mesh, previous analyses…) – From components to assembly – Throughout the design cycle – Analysis to analysis – Mesh tech. to meshing technology
Unique Merits of ANSA-TGrid Process
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Assembly
Subassembly
Component
Use Case I External Aero Dynamics Simulation Objective
– Provide accurate prediction for Drag and Lift coefficients. – Evaluate design changes for optimization to reduce drag and provide
enough down force at the same time.
Challenges for CFD Pre-processing – Capture features accurately especially on styling surfaces – Generate boundary layers to achieve y+ ~ 1 on styling surfaces – Huge cell counts for typical applications – Fast turn around – Go through large design changes rapidly
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Preprocessing Strategy for External Aero Dynamics Pristine surface mesh on styling surfaces
– Perfect feature capturing – Full control on elements size and quality – Fine resolution to resolve boundary layer
AdvWrap drive, underhood/underbody and in-cabin components
– Walk over geometry defects – Ensure leakage free surface mesh – Preserve important features – Reduce engineering time by automation
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Single-Surface and TOPO-Mesh Group
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Single-Surface and TOPO-Mesh Results
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Surface Mesh Ready for Volume Mesh
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Volume Mesh
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Heat exchanger cell zone
MRF fan zone
10 Prism layers with Min. height 0.01 mm on all styling surfaces Total cell counts ~ 34.5 M; Max. Skewness < 0.98
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Turnaround
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Subprocess Man Time (Hour)
CPU Time (Hour)
Part Management 1 N/A
AdvWrap 0.5 3
TOPO-Mesh 16 N/A
Prism Layer Validation
4 4
Connect 6 N/A
Surface Mesh Improvement
2 N/A
Volume Mesh 0.5 1.5
Total 30 8.5
Use Case II Vehicle Thermal Management Simulation Objective
– Model full vehicle to predict flow and heat transfer through cooling module. – Provide accurate temperature prediction for critical components under
difference road conditions to improve vehicle quality and reliability.
Challenges for CFD Pre-processing – Complex and dirty geometry – Separate fluid cell zones are required to model secondary fluids/flows – Separate solid cell zones are required to obtain accurate temperature
prediction in Conjugate Heat Transfer (CHT) simulation – Complex case setup – Fast turn around – Go through large design changes rapidly
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Preprocessing Strategy for Vehicle Thermal Management Individual TOPO-Mesh/wrap on components
critical to thermal analysis – High quality for thermal analysis – Ensure leakage free surface mesh – Obtain separate cell zones for secondary flows – Obtain separate cell zones for different materials – Conduction paths persevered by local connect
Single-Surface thin solids – Leverage shell conduction in FLUENT – Reduce cell count and improve mesh quality AdvWrap components not critical to thermal
analysis – Walk over geometry defects – Ensure leakage free surface mesh – Preserve important features – Reduce engineering time by automation
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Single-Surface Group and Results
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Surface Mesh Ready for Volume Mesh
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Volume Mesh
2014 Automotive Simulation World Congress 26 10 Fluid cell zones, 30.3M tet., Max. Skewness < 0.96 29 Solid cell zones, 3.05M tet., Max. Skewness < 0.95
Heat exchanger MRF fan zone Fuel tank
Cooling duct for rear brake system Monday, October 06, 2014
Solids
Simulation Results
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Shells
Turnaround
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Subprocess Man Time (Hour)
CPU Time (Hour)
Part Management 1 N/A
AdvWrap 0.5 4
TOPO-Mesh/Wrap 4 N/A
Prism Layer Validation
0.5 N/A
Connect 5 N/A
Surface Mesh Improvement
0.5 N/A
Volume Mesh 0.5 1.5
Total 12 5.5
Typical Industrial Productivity Gains
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Subprocess Method No. of days
1 Translate CAD to ANSA
2 Upper body including styled surfaces (external aero)
Topo-Mesh 5
3 Surface mesh generation (external aero) Topo-Mesh 2
4 Brakes Topo-Mesh 2
5 Part Management (for naming and wrap) Includes fixing large leakages/holes
3
6 Main wrap of UH and UB components WrapAdv.; HX+Fan
1
7 Solids surface mesh Surface-mesh or Wrap
3
8 Connect ANSA-TGrid 3
9 7 Design changes 1
Total 20
Full vehicle with all details (~10K components)
One common model built for external aero, front-end cooling, brake and thermal simulations
CAD to Solution time reduced by 3X with no sacrifice of accuracy
Maximizing efficiency across multiple teams
Subprocesses 2-4 and 5-7, executed in parallel.
Conclusion Semi-automated, streamlined workflow that employs the best of both ANSA and TGrid Increased throughput (w.r.t. man hrs and user
comfort); Reusability; Scalability Flexibility and control over mesh quality and accuracy Enables dynamic collaboration and parallel execution PLM/PDM connectivity/portability Allows for higher level of automation
And can be readily integrated in the OEMs’ processes
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Mesh Subassemblies
Volume Mesh
Geometry Operations
CAD/PLM Read-in
Part Management for Meshing
Setup Post process Solve Connect Subassemblies