Abstract: Based on unstructured finite volume method,a two-dimensional numerical model is presented with Roe type approximate Riemann solver used for flux and the characteristic decompose method is used for the bed slop source terms.The unstructured grids,which can finely describe the bridge piers,overcome the shortcoming of the local roughness refining method and the local topography changing method.The model is applied to calculate practical flow field around bridges.The results,including water level,velocity distr...