孤立波作用下破碎区单圆柱附近流动特性数值研究

Numerical study of the flow characteristics around a single pile in the surf zone under solitary waves

为了合理分析孤立波作用下破碎区单圆柱附近的水流结构以及圆柱受力特性,该文利用OpenFOAM开源程序求解基于Navier-Stokes方程的三维数值模型,该模型采用S-A IDDES湍流模型,使用修正的VOF方法捕捉自由液面。研究发现,该数值模型能合理捕捉到孤立波与圆柱相互作用过程中复杂的液面形态变化;圆柱附近自由液面沿柱面呈三维分布,上爬过程的柱前雍高显著大于回落过程的柱后雍高;回落过程中柱前形成的尾涡在强度和范围上大于上爬过程中柱后形成的尾涡;圆柱表面的动水压强随水深的增长呈近似线性增长,最大值位于上爬过程中最大雍高时刻的迎浪点位置;圆柱所受的波浪力与柱面附近自由液面雍高历时相符,且上爬过程圆柱受到的波浪力明显大于回落过程。

In order to analyze the flow characteristics and wave force around a single cylinder in the surf zone under solitary waves, a three-dimensional numerical model based on the Navier-Stokes equations was solved based on the open-source software package ‘OpenFOAM＇ in this paper. The S-A IDDES turbulence closure solver, together with modified VOF method to capture the free surface was employed. The results show that the numerical model can reproduce the solitary wave interacting with a cylinder reasonably well. The 3D distribution of wave run-up around the cylinders is evident, and the maximum run-up at the up-rush stage is significantly larger than that at the down-rush stage. Both intensity and extent of the vortex formed on the seaside of cylinder at the down-rush stage appeared to be larger than that formed on the leeside of the cylinder at the up-rush stage. The dynamic pressure around the cylinder was found to increase almost linearly with the increasing of water depth, and it reached its peak value when the maximum run-up on the seaside of the cylinder achieved. The variation of total wave force acting on the cylinder followed closely the variation of wave run-up on the cylinder, and wave force at the up-rush stage is considerably larger than that at the down-rush stage.