Abstract
Abstract
This research focuses on the analysis of the instability of passenger vehicles associated with transient crosswind gusts. A new vehicle model, created to analyze the behavior of unsteady wakes on bluff bodies, is proposed. This test model called Willy is designed using the following criteria: the geometry is realistic compared to a real vehicle, the model's plane underbody surface is parallel to the ground, and the separations are limited to the region of the base for a moderated yaw angle, i.e 10°. In the present paper, steady flow is investigated at several yaw angles, this one varies between b = -15° and b = +35°. Experiments are carried out at a Reynolds number of 0.9 106 a at the Conservatoire National des Arts et Métiers and computations are performed at the Ecole Centrale de Nantes. The ISIS-CFD flow solver, developed by the CFD Department of the Fluid Mechanics Laboratory, uses the incompressible unsteady Reynolds-averaged Navier-Stokes equations. The solver is based on the finite volume method to build the spatial discretization of the transport equations. The face-based method is generalized to two-dimensional or three-dimensional unstructured meshes for which control volumes are bounded by an arbitrary number of constitutive faces. The numerical results will be compared with experimental data. Agreement between calculation and experimentation is fairly good even for large yaw angle.
Keywords: Vehicle Aerodynamics, Cross Wind, Generic Car, Computations, Experiments