缓坡地形上移动压力源兴波的数值模拟

Numerical Simulation of Wave Resistance Induced by Moving Pressure Distributions over Mild Slope Beach

为了研究气垫船在缓坡地形上的水动力系数和兴波问题,将气垫船概化为移动压力源,建立了采用高阶非线性强色散Boussinesq方程模拟不同临界状态压力源兴波问题的数值模拟方法.采用基于自由表面边界条件作为时间步进形式的Boussinesq方程,对于势流问题采用满足Laplace方程的级数解建立了自由表面边界速度和底面边界速度之间的关系,使得数学模型封闭.通过在自由表面边界条件中增加压力分布求解出快速运动压力源的兴波问题.通过数值模拟给出了近岸缓坡上运动压力源在跨临界和超临界状态下的兴波阻力变化过程.由于地形引起的兴波变化显著地增加了缓坡地形上移动压力源的水动力系数.

In order to study the hovercraft＇s wave resistance over mild slope beach, the hovercraft was simulated as a moving distribution of pressure source. High order nonlinear and highly dispersive Boussinesq equations were used to simulate the wave field at different Froude number. The Boussinesq equations were derived from the exact nonlinear free surface boundary conditions. The velocity components at free surface and at the bottom were connected using the series solution of Laplace equations for potential flows. Thus the moving pressure distribution can be directly implemented on the free surface boundary condition. Numerical results of hydrodynamics loads and wave field were obtained for pressure distribution moving at both transcritical and supercritical speeds. The influence of mild slope bathymetry can significantly change the hydrodynamics loads.