Numerical study of aerodynamic coefficients of a ground vehicle

The objective of the present paper is to evaluate the turbulent flow around the Ahmed body immersed in air and to determine its aerodynamic coefficients for different slant angles. The bidimensional non-stationary analysis of an incompressible flow around the Ahmed body is carried out for three different rear angles which are 0°, 10° and 25°. The numerical simulations were performed under the same Reynolds number, ReL = 94 000, based on the free streamwise velocity, u, the longitudinal length of the Ahmed body, L, and the kinematic viscosity of the work fluid, ν. The additional diffusivity caused by the turbulent motion was approached using the Boussinesq’s idea through the k-ω SST. In the paper, aerodynamic coefficients of drag and the pressure and velocity fields are presented to characterize the Ahmed body for such slant angles, as well as the flow detachment point, determined through the dimensionless skin friction factor distribution on the body’s surface. The results showed that the slant presence affects the skin friction and pressure coefficients. As the slant angle was increased, the portion of pressure drag became more significant in total drag. Skin friction coefficient distribution was first presented for this body. As numerical simulations were compared with available results in open literature and showed agreement, we concluded that it was possible to simulate a problem notably tridimensional with a bidimensional simulation, leading to savings in simulation time and computational cost