Numerical simulation of bus aerodynamics on several classes of bridge decks

Abstract

This paper is focused on improving traffic safety in bridge under crosswind conditions because adverse wind conditions increase the risk of traffic accidents. In this work, two ways in order to improve traffic safety are proposed to study. Vehicle stability can be improved on the one hand by means of wind fences installed on bridge deck and on the other hand by modifying design parameters of the infrastructure. Specifically, this study examines the influence of different parameters related to bridge deck configuration on the aerodynamic coefficients acting on a bus model under crosswind conditions. The aerodynamic coefficients related to: side force; lift force and rollover moment, were obtained for three classes of bridge deck (box, girder and board) by numerical simulation. The FLUENT code was used in order to solve Reynolds-averaged Navier–Stokes (RANS) equations along with the SST turbulence model. Two crash barriers located on the box bridge deck were replaced by an articulating wind fence model and then, the effect of angle between the wind fence and the horizontal plane on the bus aerodynamic was presented. The risk of having rollover accidents is slightly influenced by the bridge deck type for a yaw angle range between 75º and 120º. In order to study the effect of yaw angle on aerodynamic coefficients acting on bus, both the bus model and bridge model were simultaneously rotated. The minimum value of rollover coefficient was obtained for an angle 60º between the wind fence slope and the horizontal plane. The only geometry parameter of box bridge deck which significantly affects bus aerodynamics is the box height. The present research highlights: the usefulness of computational fluid dynamics codes for improving traffic safety, the performance of articulating wind fence, which geometry parameters of box deck have a significant influence on bus stability.