Application of Detached-Eddy Simulation for Automotive Aerodynamics Development 2009-01-0333
This paper presents a complete methodology for performing finite-volume-based detached-eddy simulation for the prediction of aerodynamic forces and detailed flow structures of passenger vehicles developed using the open-source CFD toolbox OpenFOAM®. The main components of the methodology consist of an automatic mesh generator, a setup and initialisation utility, a DES flow solver and analysis and post-processing routines.
Validation of the predictions is done on the basis of detailed comparisons to experimental wind-tunnel data. Results for lift and drag are found to compare favourably to the experiments, with some moderate discrepancies in predicted rear lift. Point surface-pressure measurements, oil-streak images and maps of total pressure in the flow field demonstrate the approach's capabilities to predict the fine detail of complex flow regimes found in automotive aerodynamics.
Standard DES methods can cost an order of magnitude more than traditional methods, but optimisation and automation of mesh generation, setup and solution algorithms ensure quick turn-around times. Due to the fully parallel nature of these components, the entire process can be executed in a distributed fashion. Efficient solution algorithms provide exceptional accuracy when compared to Reynolds-averaged approaches without sacrificing stability, even when the flow exhibits high Courant numbers.
The proposed methodology is highly customisable, which allows for targeted developments to suit the individual needs of aerodynamics CFD. On the basis of the results presented here, the methodology is found to be appropriate and suitable for use in the industrial development process.