以Navier-Stokes方程为控制方程,使用VOF方法追踪自由液面,由连续性方程和动量方程推导出源函数。基于非线性波浪理论和UDF对FLUENT进行二次开发,在数值水槽的各个功能区将不同的源项添加到动量方程中,实现动量源造波和消波的功能。此法可以有效地消除波浪在水槽出流边界的反射及波浪遇到结构物后在入射边界形成的二次反射,从而得到稳定的波动场。本文将这种方法应用于直墙防波堤上波浪压力的数值模拟,分析了造波和消波的有效性,对直立式防波堤波浪力进行了数值研究。为了得到更精确的结果,采用结构化网格和非结构化网格相结合,在直墙防波堤附近使用三角形网格,在其他区域使用四边形结构化网格,为了较好地捕捉自由液面,在液面上下一个波高的范围内对网格进行加密。将计算结果与二阶stokes波理论解进行对比,该方法计算结果与理论解一致,表明该方法能够产生历时较长的稳定的非线性规则波浪,能够很好地吸收波浪遇到建筑物产生的反射波,可以有效消除建筑物反射波的影响,为实际工程方案的设计提供参考,有较高的实用价值。通过计算得到极端高水位,设计高水位,设计低水位时候的各个测点的最大正向波压力和最大负向波压力,并将计算结果与物理模型试验数据和经验公式结果进行对比,结果吻合较好。并且由于该数值方法可以考虑防波堤迎浪面不同倾角的工况,其适应范围比经验公式范围更广,因此可以为海岸结构设计提供依据。

Based on Navier-Stokes equations to describe the motion of incompressible fluid,the volume of fluid(VOF)method is adopted to track the free surface.According to the continuity equation and momentum equation,the source function is deduced.Different source terms will be added to the momentum equation in each functional area of the numerical flume on the basis of nonlinear theory of wave(second-order Stokes)and the UDF function of the secondary development of FLUENT software to realize the functions of wave generation and absorption.By this method wave reflection at outflow boundary and secondary reflection at the incident boundary from a marine structure.can effectively eliminated in order to obtain stable wave field.This approach is applied to the numerical simulation of wave pressure on vertical breakwater.The effectiveness of wave making and wave elimination is analyzed.Then,the numerical simulation of wave pressure on vertical breakwater is carried out.To realize the accuracy of the calculation and the high efficiency,the flow field is meshed by structured and unstructured grids.Triangular mesh is used near the vertical breakwater and structured grid is used in other regions.The mesh of a wave height in the free surface needs to be densified in order to capture the free surface better.Results are consistent with the theoretical solution of second-order non-linear Stokes wave.This shows that the proposed numerical wave flume based on software FLUENT could eliminate the second reflecting wave of building and realize long time of wave.It provides reference for the design of practical engineering project,and has high practical value.The maximum forward wave pressure and the maximum negative pressure of each measurement point are calculated at extreme high water level,design high water level and low water level.The results compared with both experimental data and the results by empirical equations show that simulated wave pressure fit measured results very well.In addition,the numerical method can be used to calculate the various conditions with different angles of breakwater slope.Because the numerical calculation can be applied in a wider scale than empirical equation method,its results can provide a solid support for coastal structural design.