Comparison of Numerical Simulations with Experiments of Bluff Bodies Including Under-Hood Flow 2011-01-0171

Computational Fluid Dynamics (CFD) is state of the art in the aerodynamic development process of vehicles nowadays. With increasing computer power the numerical simulations including meshing and turbulence modeling are capturing the complex geometry of vehicles and the flow field behavior around and behind a bluff body in more detail. The ultimate goal for realistic automotive simulations is to model the under-hood as well.

In this study vehicle simulations using the finite volume open source CFD program OpenFOAM® are validated with own experiments on a modified generic quarter-scale SAE body with under-hood flow. A model radiator was included to take account of the pressure drop in the under-hood compartment. Force and pressure measurements around the car, total-pressure and hot-wire measurements in the car flow field and surface flow patterns were simulated and compared with the experiment. The simulations are performed using a virtual wind tunnel which provides correct boundary-layer treatment and test-section pressure gradient compared to the experiment. Different approaches of turbulence modeling were investigated, RANS and DDES simulations are performed and compared with each other and with own experiments.

For industrial usage of the computation process, a porous media for the model radiator was implemented and validated in OpenFOAM®. A process including meshing, solving and post-processing was developed and validated with experiments. The result is a completely validated numerical process.