一种河道紊流三维数值模拟离散格式的应用探讨

通过引用气体动力学中的Osher格式计算控制体交界面通量,建立了一种基于有限体积法的河道紊流三维数学模型。该格式是对准确的非线性黎曼问题的近似解法,具有很好的守恒性、逆风性、单调性和高分辨率捕捉间断的能力,解决了河床变化剧烈处水流计算易发散的难题,在紊流模型的选取上,考虑到紊动能量和紊动尺度在水平方向和垂直方向上的差异,平面上采用大涡模型,垂向上采用k-ε模型。通过桥墩和丁坝局部水流实测资料校核模型模拟局部复杂水流结构的能力,模型计算得到的马蹄涡、回流结构及流速分布与实测基本一致。

Improvement and application of 3D numerical discretization scheme for riverway turbulence

New 3D mathematical model for riverway turbulence is established by using 3D numerial discretization scheme,in which the Osher′s scheme with superior properties in aerodynamics is used to compute the horizontal flux through the interface of two adjacent finite volumes.The scheme is the approximate solution for accurate nonlinear Riemann problem,thus the model has a good property of conservation for physical quantity,up-wind property,monotonic-reserving,high resolution in capturing discontinuity.The difficult problem of flow calculation easily diffusion in the dramatic changes riverbed is solved.When selecting the turbulence model,the difference of turbulence energy and turbulence scale in the horizontal direction and vertical direction is considered,large eddy simulation model and k-ε model is adopted respectively in the horizontal and vertical direction.Based on the pier and dike local flow measured data,the ability of simulating local complicated flow was checked,the results show that horseshoe vortex、recirculation constitution and flow velocity distribution which are obtained by computation are similar to the measured results.