OPENFOAM VALIDATION CASES
DrivAer validation case - Automotive simulation
Hereafter, we compute the flow about the DrivAer model [1]. This is an automotive validation case that has extensive experimental data [1, 2, 3]. The simulations presented in this validation case, were conducted for the fastback and smooth underbody model. The inlet velocity corresponds to 30 m/s, the ground is moving with a translational wall boundary condition, and the wheels are rotating with a rotational wall boundary condition.
The simulations were conducted using simpleFoam and the k-Omega SST turbulence model with wall functions. The boundary and initial conditions for the turbulence quantities were computed using the guidelines described in reference [4]. At the outlet of the domain, we used backflow treatment.
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| Drivaer model. The geometry corresponds to the fastback and smooth underbody model [1] |
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| Boundary conditions |
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| Moving wall boundary conditions |
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Visualization of vortical structures using Q-criterion |
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Visualization of velocity magnitude contours in the symmetry plane. Visualization of pressure contours and streamlines of the model surface. |
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| Drag coefficient iterative converge. Setup 1: no rotating wheels, moving ground. Setup 2: rotating wheels, moving ground. Setup 3: rotating wheels, no moving ground. Setup 4: no rotating wheels, no moving ground. |
| Reference | Mean \( c_d \) |
|---|---|
| Current validation study (Setup 2) - OpenFOAM | 0.2426 |
| Ref. [2] - EXP PVT UC | 0.243 |
| Ref. [2] - EXP PVT | 0.228 |
| Ref. [2] - EXP TUM ASME | 0.247 |
| Ref. [2] - EXP TUM SA | 0.243 |
| Ref. [2] - NUM US:200M | 0.235 |
| Ref. [2] - NUM SS-EWT:200M | 0.214 |
| Ref. [3] | 0.258 |
Table 1: comparison of experimental and numerical results. Setup 2 corresponds to the simulation with moving ground and rotating wheels. The mesh used is made up of approximately 8 000 000 cells and the average y+ value is close to 50.
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| Residuals iterative evolution. Only the first 1000 iterations are shown. All the simulations were run up to 5000 iterations. |
warning The experimental values were extracted from plots illustrated in references [1, 2, 3].
We can not guarantee the accuracy or precision of this information.
References:
[1] https://www.epc.ed.tum.de/en/aer/research-groups/automotive/drivaer/
[2] Steady and Unsteady Numerical Analysis of the DrivAer Model. R. Yazdani. Chalmers University of Technology, Master Thesis, 2015.
[3] Experimental Comparison of the Aerodynamic Behavior of Fastback and Notchback DrivAer Models. SAE Technical Paper 2014-01-0613, 2014.
[4] https://turbmodels.larc.nasa.gov/
Download here the case files - OpenFOAM 9 (coarse mesh).
Download here the case files - OpenFOAM 9 (fine mesh).
Download here the case presentation slides.
Acknowledgements:
We would like to thanks Marco Giachi for the enlightening discussions, valuable suggestions, and sharing his setup as a starting point for developing this validation case. If you want to know more about Marco’s work, look for his book in Amazon: link 1, link 2.
