Aerodynamic Shape Optimization of a Double-Deck Bus Subjected to a 30 Degree Side Wind Using CFD and Response Surface Models

Report, 2008

Directional stability and passenger comfort are of great concern in the case of a double-deck bus subjected to a side wind. Since the shape of the bus to a lar ge extend determines its aerodynamics, a proper design is needed to avoid the co nsequences of a large side force. In this paper, we proposed the use of CFD-base d design with a response surface models to construct the optimum shape for a dou ble-deck bus subjected to a side wind with a $30^o$ yaw angle. The primary objec tive is to minimize its aerodynamic coefficients by changing the radius and angl e of its front face. The results show that increasing the curvature of the front face increases the side force and the yaw moment coefficients, while the front angle has little influence on the bus aerodynamics. The Pareto-optimal front is constructed to relate two aerodynamic coefficients in the range of the design v ariables. In general, the CFD-based design with the response surface model shows a promising and cheap alternative to the wind tunnel experiments and the tradit ional trial and error method.