Experimental and Numerical Analysis of the Effect of Side Wind on a Simplified Car Model 2007-01-0108

The general objective of this research is the analysis of the instability of passenger vehicles associated with transient crosswind gusts. Experimental and numerical tests are performed on the squareback Willy test model, which is realistic compared to a van-type vehicle. Experiments were carried out in a semi-open test section at the Conservatoire National des Arts et Métiers (CNAM) and computations were performed at the Ecole Centrale de Nantes (ECN). The ISIS-CFD flow solver, developed by the CFD Department of the Fluid Mechanics Laboratory of ECN used the incompressible unsteady Reynolds-averaged Navier-Stokes equations. The experimental results obtained at a Reynolds number of 0.9 10⁶ were compared with numerical data for steady flow. Agreement between experimental and computed aerodynamic forces, wall pressures, and tomographies of total pressure is fairly good. Results are completed by the first results concerning phase shifts, and hysteresis phenomena for the wall pressure on the windward and leeward sides of the model subjected to an harmonic oscillation along its vertical axis.