为了得到涌潮冲击丁坝过程中流场、自由液面及压力的变化规律,建立涌潮冲击排桩式丁坝的三维数值模型,采用有限体积法对控制方程进行离散,利用压力隐式算子分割法(PISO)求解雷诺时均方程和RNGκ-ε紊流模型,应用体积函数(VOF)法追踪自由表面,计算结果与水槽试验吻合较好,并得出如下结论:(1)涌潮冲击丁坝时产生壅水、翻越、绕流等现象,丁坝排桩附近流线密集,水速变化快,坝头背水面产生涡流;(2)丁坝迎水面压力在坝根和坝脚处较大,其最大值随潮高、初始水深的增加都线性增大,并在透水率增加时降幅变大;(3)前排桩两侧压力差在坝头和初始水面处较大,并在水面上、下都线性减小,其最大值在潮高增加时增幅变大,在透水率增加时降幅变大,并且在不同初始水深下变化不大.后排桩两侧压力差在坝头和坝顶处较大.
A three-dimensional numerical model of bore against sheet-pile groin was illustrated.The governing equations were discredited by the finite volume method,and the Reynolds equations and the RNGκ-ε turbulent model were solved by the pressure implicit splitting-operator(PISO)method.The position of free surface was obtained by using the volume of fluid(VOF)method.The model was verified by the flume experiment research with the comparison between the numerical results and experimental data in good agreement.The proposed model can be used to simulate the velocity vectors,free water surface,bore pressure of a groin:(1)The flow near the groin changes strongly with backwater,hydraulic jump and vortex behind the head of groin when the bore impacts the groin;(2)The pressure is much larger at the toe and root of groin on the impacted surface and the maximum pressure increases linearly with the bore height and the initial water depth respectively,while it decreases rapidly when the water permeability rate enlarges;(3)The pressure of front piles is larger at the root of groin,and it is linear distribution along the height with the maximum value at the initial water surface,and the maximum pressure increases quickly when the bore height accretes,while it has a rapid decrease when the water permeability rate enlarges,but it has little change under different initial depths.The maximum pressure of back piles is at the head and the top of groin.