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A study was conducted using Ford's nine standard CFD calibration models as described in SAE paper 940323. The models are identical from the B-pillar forward but have different back end configurations. These models were created for the purpose of evaluating the effect of back end geometry variations on aerodynamic lift and drag. Detailed experimental data is available for each model in the form of surface pressure data, surface flow visualization, and wake flow field measurements in addition to aerodynamic lift and drag values. This data is extremely useful in analyzing the accuracy of the numerical simulations. The objective of this study was to determine the capability of a digital physics based commercial CFD code, PowerFLOW ® to accurately simulate the physics of the flow field around the car-like benchmark shapes.

Several studies have been conducted in an effort to bring Computational Fluid Dynamics (CFD) out of the research arena (5) and into the product design environment as a useful aerodynamic design tool. The focus of these studies has ranged from extremely simple shapes to more complex geometries representative of real vehicles. This paper presents the results of real vehicle applications in which CFD was used to predict the aerodynamic effect of proposed surface modifications. The simulation data was generated using a numerical method derived from lattice gas theory to evaluate the aerodynamic effect of surface modifications. The commercial software Powerflow was used to prepare the model, perform the simulation and post-process the results. These case studies were performed in parallel with real vehicle development programs. The depth of experimental comparison data was limited by traditional vehicle program timing and budget constraints.