Large Eddy Simulation of Aerodynamics of a Flat Box Girder on Long-span Bridges

Abstract

The wind field around a box girder of a large span cable-stayed bridge, under Reynolds number of Re=1.27×105 in uniform flow, is computed by using three-dimensional large eddy simulation (LES). The LES employs the Smagorinsky subgrid turbulent model. The averaged drag, lift and moment coefficients, as well as the Strouhal number at various angles of attack are obtained. The research shows that the vortex shedding period changes with time, and vortices do not shed synchronously in span-wise direction, while the vortex shedding energy concentrates on a narrow band of frequency. The distribution of mean and root-mean-square value of pressure around the girder surface is also provided, as to represent the flow separation and reattachment pattern on the girder surface. The present results are compared with results from wind tunnel test. It is confirmed that the LES is capable of investigating the aerodynamics of bridge girders and flow mechanism.