A Numerical Simulation on the Drag Reduction of Large-Sized Bus using Rear-Spoiler 2002-01-3070

The aerodynamic characteristics of automobiles have received substantial interest recently. Detailed knowledge of vehicle aerodynamics is essential to improve fuel efficiency and enhance stability at high-speed cruising. In this study, a numerical simulation has been carried out for three-dimensional turbulent flows around a commercial bus body. Also, the effect of a rear-spoiler attached at the rear end of the bus body was investigated. The Navier-Stokes equation is solved with the SIMPLE method in a general curvilinear coordinates system. RNG k- ε turbulence model with the MARS scheme was used for evaluating aerodynamic forces, velocity and pressure distribution. The results show that complex wake structure in the immediate rear of the bus body has been confirmed. The rear-spoiler modifies the near wake structure and decreases aerodynamic drag and improvement in lift force was achieved.