桥渡对河道水流影响的二维无结构网格模型

Two-dimensional unstructured finite volume model for bridge pier flow

采用有限体积法建立平面二维水流运动的无结构网格数学模型,模型采用Roe格式的近似Riemann解计算界面通量和特征分解法处理底坡源项.通过无结构网格对桥墩形状进行精细拟合克服了局部糙率修正、局部地形修正等方法的困难,为研究桥墩、桥形等对水位、局部流速等建桥前后的变化提供了新的计算模式.最后,应用模型对河段上的圆形墩和圆端矩形墩壅水进行了模拟,结果表明模型能够较好的模拟建桥前后桥墩附近的水流变化.

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 distribution, discharge ratio between branches and choked flow field, are satisfactory. This mathematical model can be used as a matching tool to the physical model testing in studying bridge pier choked flows.