数值波浪水槽中完全非线性浅水波仿真特性研究

Study on the characteristics of simulating the fully nonlinear shadow water waves in numerical wave tank

应用基于势流理论的时域高阶边界元方法,建立一个完全非线性的三维数值波浪水槽,通过实时模拟推板造波运动的方式产生波浪。通过混合欧拉拉格朗日方法和四阶Runge-Kutta方法更新自由水面和造波板的瞬时位置。利用所建模型分别模拟了有限水深波和浅水波,与试验结果、相关文献结果和浅水理论结果吻合较好,且波浪能够稳定传播。系统地讨论造波板的运动圆频率、振幅和水深等对波浪传播和波浪特性的影响,并对波浪的非线性特性进行分析,研究发现造波板运动频率、运动振幅以及水深均将对波浪形态和波浪非线性产生显著影响。结果为真实水槽造波机的运动控制以及波浪生成试验提供了依据,便于实验室设置更合理的参数来准确模拟不同条件下的波浪。

In order to investigate the influences of wave maker motion on wave propagation, a 3D fully nonlinear numerical wave tank model is developed in the potential theory frame. The time domain higher-order boundary element method is used in the proposed model and the mixed Eulerian-Lagrangian approach is adopted to update the instantaneous free surface. Numerical experiments are carried out to simulate finite depth waves and shallow water waves at different input amplitudes, frequencies and depths. Waves can travel steadily and wave profiles turn out to be steady and in good agreement with the experimental results, analytical solutions and results published before. The influence of wave frequency, amplitude and water depth on wave propagation and wave characteristics is studied and discussed. It is found that the wave shape and wave nonlinearity are significantly affected by the frequency, amplitude and water depth. The results provide a basis for the motion control and wave generation test of a real wave generator in a flume, and more reasonable parameters can be set in the laboratory to accurately simulate waves under different conditions.