Large-eddy simulation of flows past complex truss structures

Numerical simulation of turbulent flows past typical truss structures that are common in bridges and towers has been conducted. Large-eddy simulation (LES) method is used that has been verified in computing flows past simple bodies at moderate Reynolds numbers. Truss structures consist of thin members that are too small to be accurately resolved by numerical grids that can be handled by most computer systems. It has been found that when the individual members are long angular bars, the overall flow can be reproduced fairly well by approximating the members with rectangular cylinders whose cross sections are resolved by more than 2×2 computational cells and by taking computational regions extending at least four structure heights downstream and about three heights across the vertical and spanwise directions. The drag coefficient and the vortex shedding characteristics along with the complex wake structures associated with the truss structures are reproduced reasonably well.