A NUMERICAL SIMULATION OF THE FLOW AND VORTEX STRUCTURES AROUND A SIMPLIFIED CAR MODEL
Keywords:
ASMO model, SLH, OpenFOAM, automobile aerodynamicsAbstract
The ASMO model exhibits many of the 3D flow structures exhibited by real passenger
cars. The scope of this work is an analysis of the applicability of the open-source CFD toolbox
OpenFOAM for the prediction of external automobile aerodynamics using steady/unsteady RANS
simulation as well as hybrid RANS-LES in combination with unstructured grids including up to
5×10 6 cells. This work is investigating the drag, lift, and pressure coefficient, flow field and flow
structures in the rear section of the ASMO model using steady and unsteady RANS and hybrid
RANS-LES. The results are validated by using experimental measurements by Daimler and
Volvo. The flow structures around the ASMO model are constructed by using different vortex
identification criteria. The inlet velocity is changed to know its influence. The results show that
k−ω−SST gives the best for steady simulation and IDDES for unsteady simulation. IDDES can
capture small vortices in the rear area of the ASMO model. Reduction of inlet velocity is affected
the SLH simulation result because it is dependent on the flow separation. In conclusion, hybrid
URANS-LES is the best model to study the aerodynamics of car models compared to URANS
simulation.
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