Download - 2nd Automotive CFD Prediction
2nd Automotive CFD Prediction
WorkshopMarian Zastawny, Peter Altmann, Sylvain Lardeau
Siemens Digital Industries Software
UnrestrictedUnrestricted | © Siemens 2021 | 2021-08-26 | Marian Zastawny | 2nd Automotive CFD Prediction Workshop | Siemens Digital Industries Software | Where today meets tomorrow.
Simcenter STAR-CCM+
Unrestricted | © Siemens 2021 | 2021-08-26 | Marian Zastawny | 2nd Automotive CFD Prediction Workshop | Siemens Digital Industries Software | Where today meets tomorrow.Page 2
Tessellated Surface
Wrapped Surface
Remeshed Surface
0%
25%
50%
75%
100%
0
448
896
1,344
1,792
0 448 896 1,344 1,792
SC
ALIN
G
SP
EE
D U
P
CORES
Complex Geometry Handling
Speed and Performance
Accurate Physics
Robust and Precise Meshing
Workflow Automation
Intelligent Design Exploration
Turbulence Modelling
Unrestricted | © Siemens 2021 | 2021-08-26 | Marian Zastawny | 2nd Automotive CFD Prediction Workshop | Siemens Digital Industries Software | Where today meets tomorrow.Page 3
Statistical model (RANS)
SA
1. Standard
2. High-Re
k-e
3. Std.
4. Std. 2-layer
5. Std. low-Re
6. Realizable
7. Real. 2-layer
8. AKN
9. V2-f
10. EB k-e
11. Lag EB k-e
k-w
12. Standard
13. SST
RSM
14. Linear pressure-strain
15. Quad. Pressure-strain
16. EB-RSM
Scale-Resolving
DES
17. SA
18. SST k-w
19. EB k-e
LES
20. Smagorinsky
21. WALE
22. Dynamic Smagorignsky
Cost
Influence of modelling assumptions
Influence of user input
Robustness
Model
High
Low
Why to use SRS in automotive?
Unrestricted | © Siemens 2021 | 2021-08-26 | Marian Zastawny | 2nd Automotive CFD Prediction Workshop | Siemens Digital Industries Software | Where today meets tomorrow.Page 4
Windsor Body RANS
Unrestricted | © Siemens 2021 | 2021-08-26 | Marian Zastawny | 2nd Automotive CFD Prediction Workshop | Siemens Digital Industries Software | Where today meets tomorrow.Page 5
Analysed results
Unrestricted | © Siemens 2021 | 2021-08-26 | Marian Zastawny | 2nd Automotive CFD Prediction Workshop | Siemens Digital Industries Software | Where today meets tomorrow.Page 6
Wall-Modelled RANS
Unrestricted | © Siemens 2021 | 2021-08-26 | Marian Zastawny | 2nd Automotive CFD Prediction Workshop | Siemens Digital Industries Software | Where today meets tomorrow.Page 7
SST, a1 = 1.0 Lag EB
Wall-Resolved RANS
Unrestricted | © Siemens 2021 | 2021-08-26 | Marian Zastawny | 2nd Automotive CFD Prediction Workshop | Siemens Digital Industries Software | Where today meets tomorrow.Page 8
SST, a1 = 1.0 Lag EB
RANS Comparison
• Wall-Modelled RANS appears to be closer to
experiment than Wall-Resolved RANS
• SST (a1=1) predicts higher drag coeffcients
• Wake prediction is somewhat correlated with the
reported forces
• Change in velocity profiles is less substantial than
change in drag coefficient
Unrestricted | © Siemens 2021 | 2021-08-26 | Marian Zastawny | 2nd Automotive CFD Prediction Workshop | Siemens Digital Industries Software | Where today meets tomorrow.Page 9
Windsor Body SRS
Unrestricted | © Siemens 2021 | 2021-08-26 | Marian Zastawny | 2nd Automotive CFD Prediction Workshop | Siemens Digital Industries Software | Where today meets tomorrow.Page 10
Wall-Modelled DDES
Unrestricted | © Siemens 2021 | 2021-08-26 | Marian Zastawny | 2nd Automotive CFD Prediction Workshop | Siemens Digital Industries Software | Where today meets tomorrow.Page 12
Wall-Resolved DDES
Unrestricted | © Siemens 2021 | 2021-08-26 | Marian Zastawny | 2nd Automotive CFD Prediction Workshop | Siemens Digital Industries Software | Where today meets tomorrow.Page 13
DDES Summary
Unrestricted | © Siemens 2021 | 2021-08-26 | Marian Zastawny | 2nd Automotive CFD Prediction Workshop | Siemens Digital Industries Software | Where today meets tomorrow.Page 14
• Mean flow solution is achieved almost
instantaneously
• Wake prediction is visibly better than in
RANS
• Wall-Modelled mesh simulation appears to
agree more with the experiment
• Agreement in wake prediction is correlated
with the agreement in reported forces
Scale-Resolving Hybrid (SRH) Turbulence Model
Model Description
When to Use it?
Typical Applications
• Increased fidelity unsteady RANS type modeling
• Higher accuracy than comparable URANS models
• Enhanced temporal modeling for increased realism
• Enables potential accuracy improvement to existing URANS
simulations
• Minimal additional computational cost
• Minimal work for setting up
• Mid-fidelity unsteady applications
• Applications where URANS previously was used
Increased fidelity URANS
URANS
SRH
Unrestricted | © Siemens 2021 | Version 2021.2 | Siemens Digital Industries Software | Where today meets tomorrow.Page 15
Wall-Modelled SRH
Unrestricted | © Siemens 2021 | 2021-08-26 | Marian Zastawny | 2nd Automotive CFD Prediction Workshop | Siemens Digital Industries Software | Where today meets tomorrow.Page 16
Wall-Resolved SRH
Unrestricted | © Siemens 2021 | 2021-08-26 | Marian Zastawny | 2nd Automotive CFD Prediction Workshop | Siemens Digital Industries Software | Where today meets tomorrow.Page 17
DDES vs SRH
Unrestricted | © Siemens 2021 | 2021-08-26 | Marian Zastawny | 2nd Automotive CFD Prediction Workshop | Siemens Digital Industries Software | Where today meets tomorrow.Page 18
• Impact of changing the mesh is the same for
SRH as for DDES
• SRH profiles are generally in better
agreement with experiment than DDES
• SRH shows less sensitivity with respect to
the numerical set-up
DrivAer
Unrestricted | © Siemens 2021 | 2021-08-26 | Marian Zastawny | 2nd Automotive CFD Prediction Workshop | Siemens Digital Industries Software | Where today meets tomorrow.Page 21
Summary
Unrestricted | © Siemens 2021 | 2021-08-26 | Marian Zastawny | 2nd Automotive CFD Prediction Workshop | Siemens Digital Industries Software | Where today meets tomorrow.Page 22
Forces Comparison
Unrestricted | © Siemens 2021 | 2021-08-26 | Marian Zastawny | 2nd Automotive CFD Prediction Workshop | Siemens Digital Industries Software | Where today meets tomorrow.Page 23
RANS Scale-Resolved
Open questions
• Impact of time-step
• Impact of numerical discretization
• Impact of the tunnel walls on CL and CM
• Sensitivity to Boundary Conditions
Unrestricted | © Siemens 2021 | 2021-08-26 | Marian Zastawny | 2nd Automotive CFD Prediction Workshop | Siemens Digital Industries Software | Where today meets tomorrow.Page 24
ContactMarian Zastawny
Senior Application Engineer200 Shepherds Bush Road
W6 7NL London
United Kingdom
E-mail [email protected]
Unrestricted | © Siemens 2021 | 2021-08-26 | Marian Zastawny | 2nd Automotive CFD Prediction Workshop | Siemens Digital Industries Software | Where today meets tomorrow.Page 25