基于非结构网格的三维水流数值模拟研究

Numerical simulation of three dimensional flow based on unstructured grids

【目的】以黄河沙坡头连续弯道段的水流运动为研究对象,研究非结构网格在天然河道数值模拟中的应用。【方法】建立三维紊流数学模型,采用有限体积法离散模型方程,利用SIMPLEC算法求解离散后的方程组。用非结构网格剖分研究区域,用等距分层法进行垂向分层,研究弯道水流表层、中层及底层平面流场和连续弯道典型断面处的纵向流速及环流分布,并对比分析横断面纵向流速的计算值与实测值。【结果】横断面纵向流速的计算值与实测值吻合较好。弯道水流底层到表层流速逐渐增大,在流速变化较大的地方出现了主流与深泓线分离的现象。弯道横向环流明显,表层流速指向凹岸,底层流速指向凸岸。【结论】非结构网格能较好地模拟天然河道中复杂的水流结构。

【Objective】In order to study the application of unstructured mesh in the numerical simulation of natural river,the water flow in the continuous curve section of Shapotou reach in the Yellow River was studied.【Method】A mathematical model of three dimensional turbulence was established.The finite volume method was used to discretize the model equation,and the discrete equations was solved by SIMPLEC algorithm.The study area was divided by unstructured meshes,and the vertical grid was divided by equidistant hierarchical method.【Result】The longitudinal velocity and circulation distribution of the surface,middle and bottom plane flow fields and the typical section of the continuous curve were studied,and the calculated and measured values of longitudinal velocity were compared and analyzed.The calculated values of the longitudinal velocity of the cross section were in good agreement with the measured values.The flow velocity of the bottom layer to the surface layer increased gradually,and the mainstream and thalweg were separated in the place where the flow velocity changed greatly.The surface water of bend circulation flowed to the concave bank,and the bottom water flowed to the convex bank.【Conclusion】The unstructured grid can simulate the complex flow structure in natural river.