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 numerically at several yaw angles, this one varies between 0 degrees and 30
degrees. Experiments are carried out at a Reynolds number of 0.9 10 6 by F. Chometon at the
Conservatoire National des Arts et Métiers (CNAM). Computations are carried out under the
same conditions as in the experiments. The ISIS-CFD flow solver, developed by the CFD
Department of the Fluid Mechanics Laboratory of the Ecole Centrale of Nantes, 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 are compared with experimental data such as the forces, the pressure,
the total pressure. Agreement between calculation and experimentation is fairly good even
for large yaw angle.
Keywords - Automotive flow, car model, yaw angle, numerical simulations, crosswind