CFD analysis of a tractor-trailer models drag coefficient under crosswind effect

In this study, drag coefficient of a tractor-trailer model for various yaw angles is researched by CFD. During development studies, Fluent's DES and RANS turbulence models (realizable k-epsilon, Spalart Allmaras and SST k-omega) are investigated. It is determined DES realizable k-epsilon is the optimum model that is most efficient and gives accurate results where applicable. Besides, it is observed that to improve the quality of volume mesh on leeward direction by widening size boxes is important when the yaw angle is different from 0o. Boundary layer, time step, discritization method, under relaxation factor and Cdes are investigated to calibrate the method created. The vehicle's drag coefficient is calculated by WFT aerodynamics test and an analysis method which is correlated with the results is developed.