Unsteady Aerodynamics of an Oscillating Fastback Model

Abstract

This paper investigates the surface pressures found on the sides of a Davis model under steady state conditions and during yawed oscillations at a reduced frequency which would generally be assumed to give a quasi-static response. The surface pressures are used to investigate the flow field and integrated to infer aerodynamic loads. The results show hysteresis in the oscillating model's results, most strongly in the A-pillar flows. The changes to the flow field reduce strength of the flows around the rear pillars, reduce the strength and extent of the A-pillar vortex and cause the surface pressures to couple with the oscillating motion. This work shows the flows around the front of a vehicle may be more important to a vehicle's unsteady aerodynamics than is generally accepted and also leads to the conclusions that the reduced frequency parameter may not fully describe the onset unsteadiness.

Validation of CFD Modeling and Simulation of a Simplified Automotive Model

“…The two Davis model configurations used in this paper have been previously used by [4] and [5] which allowing for direct comparisons of the simulation results presented in this paper with their previously published experimental works. Both works were conducted in the Loughborough University 1/4 scale wind tunnel.…”

“…Most common turbulence models including k-ε standard, k-ε realizable, k-ω standard and k-ω SST are tested in this study. Simulation generated centerline pressure distribution over the top surface of the round-edged model had been compared with data collected using Electronic Pressure Scanners as in reference [4]. Results from k-ε standard and k-ε realizable turbulence model correlated poorly against the experimental results compare to the two kω models and it was observed that k-ω SST model provided the closest agreement in pressure coefficient values against the experimental test data as in Fig.…”