有限尾水深波浪底板壁面射流水力特性的数值模拟研究

Numerical simulation study on hydraulic characteristics of wall jets on corrugated beds with limited tailwater

采用VOF(Volume of Fluid)方法追踪自由液面,辅以Realizable(可实现化)κ-ε湍流模型封闭两相流时均方程,对有限尾水深波浪底板壁面射流水力特性进行了数值模拟。微分方程的离散采用有限体积法,速度与压力耦合求解使用了压力隐式算子分裂PISO(Pressure-Implicit with Splitting of Operators)算法。分析了入射速度和底板粗糙度对流场流线分布、横断面最大流速沿程衰减规律、底板压强分布规律等水力特性的影响。研究发现:流场内存在两个大的漩涡,而且波浪底板凹面附近存在有小的漩涡;入射流速越大,横断面最大流速沿程衰减梯度越大;波浪底板上的压强也呈波状分布,且压强大小主要受入射流速和底板粗糙度两个因素的影响。

The VOF(Volume of Fluid) method is applied to track free water surface, and the Realizable k-ε turbulent model is used to close the two-phase flow time-averaged equations. The hydraulic characteristics of wall jets on corrugated beds with limited tailwater are studied by numerical simulation. The finite volume method is used to discretize the differential equations, and the coupling velocity and pressure equations are solved with the pressure-implicit method of splitting operators(PISO) algorithm. Influences of the incoming velocity and the roughness of beds on the characteristics of streamline distribution, the variation of the maximum velocities on cross-sections along the flowing direction, and pressure distribution on corrugated beds are studied and analyzed in the flow field. It is found that there are two big vortexes exist in the flow field, and some small vortexes exist near the concave side of the corrugated beds. The decaying gradient of maximum velocities on cross-sections increases with an increase of the incoming velocity. The pressure distribution on the corrugated beds appears wave-shape change, and the pressure values are affected by the incoming velocity and the roughness of beds mainly.