孤立波作用下边界层的模拟与分析

孤立波作用下的边界层内的剪切力以及涡量变化对海啸传播和海底地形塑造十分重要。本文基于多区域谱方法,利用直接模拟(DNS)数值模型,对在具有矩形断面的U形水洞内的孤立波下的边界层流动进行了模拟。将数值模拟结果与解析解以及试验结果进行了对比,发现数值结果与后两者吻合得较好。模拟结果显示,在低雷诺数下,扰动不会改变流态,而随着雷诺数的增大,流态会变得十分复杂。中等雷诺数情况下,边界层内会产生正向的涡,并进行稳定的传播。在较高雷诺数情况下,流动进入层流向紊流发展的过渡期,此时边界层内会产生正涡以及负涡,并会在水深方向进行不规则运动。

Simulation and analysis of boundary layer under the solitary wave

The shear stress and vortex tube in the boundary layer are very important to tsunami propagation and underwater terrain under the solitary wave. This paper takes advantage of direct numerical simulation method (DNS) to simulate the boundary layer under the solitary wave in a U shape water tunnel, based on the spectral multi-domain model. By comparing numerical results with analytical solutions and experimental results,it is found that they agree with each other well. The numerical results show that with a low Reynolds number,the disturbance does not change the flow pattern,and with the increase of Reynolds number, flow pattern will become very complicated. Within a medium Reynolds number, positive vortex tube will appear in the boundary layer, and transport stably. Under the condition of a high Reynolds number,layer flow changes into a transition period of turbulence flow and positive vorticity and negative vorticity appear in the boundary layer,and have oscillating development.