Aerodynamics of road vehicles in transient cross-winds-coupling aero to vehicle dynamics

Ground vehicles are sensitive to crosswinds, affecting aerodynamic and handling performance, and in some cases safety. Therefore it is important to be able to predict vehicle performance when exposed to crosswinds. The aim of the work presented in this paper is to assess the order of the model complexity in order to capture the vehicle behaviour during a transient crosswind event, regarding the interaction of the aerodynamic forces and the vehicle dynamic response. That is, the necessity to perform a full dynamic coupling instead of a static coupling to capture the vehicle performance both with respect to aerodynamics and the vehicle dynamics as is done today. The model used in the computations is based on the Ground Transportation System (GTS) model, which is simulated to run on a road passing a crosswind passage. The aerodynamic computations are performed using Detached Eddy Simulation (DES) coupled to a bicycle model for the vehicle dynamics. Here, two degrees of freedom are considered, that is, lateral translation and yaw motion. The change of the vehicle position in the aerodynamic domain is enabled through the use of the overset mesh technique. The results show that the full dynamic coupling is needed for large yaw angles of the vehicle, where the static coupling over-predicts the aerodynamic loads and in turn the vehicle motion.
QC 20161101