Numerical simulations on aerodynamics drag of heavy vehicle trucks

The present work investigates the aerodynamic drag characteristics of a heavy duty truck. The aerodynamic drag of a truck depends on geometry, frontal area, and the presence of a gap between the tractor and the trailer, and the speed of the truck. The basic geometry used in the study is 1:8 scale class-8 van type tractor trailer Ground Transportation System (GTS). Computational fluid dynamics analysis was performed using commercial CFD software CFX 5.6. The effects of vehicle geometry, vehicle speed, and the gap size were investigated and the drag coefficients were computed. The effects of yaw angle and add-on devices on the drag coefficient were also investigated. Finally, effect of aerodynamic drag on fuel economy was discussed. Analysis was validated by solving the drag forces on a sphere in CFX-5.6 and comparing the results with the experimental data.; The results showed that the geometry of the truck is the controlling parameter of aerodynamic drag of the trucks. Two of the most important parameters to reduce drag are the frontal area and the gap size. The present study showed that changes in the design of the truck including minimum gap between the tractor and the trailer, eliminating sharp edges around the cab and trailer, providing slight slant angle on trailer rear edges, and avoiding mismatch between tractor and trailer could reduce drag forces with significant savings in fuel and transportation costs.