针对直接给定波浪入射边界条件时数值模型不能有效计算反射波的弊端,提出吸收入射边界上反射波的方法.该方法首先在离入射边界约1/2波长的范围内,计算入射波的理论解;然后将数值解减去理论解,得到真正反射波或由于数值累计误差所产生的伪反射波;再对反射波进行消波.结合非线性波传播数值模型,通过对水深均匀和具有水深复杂变化的台阶地形的水槽内波浪传播的数值模拟,说明所提出吸收入射边界上反射波的方法能有效消除反射波对入射边界的影响.
This paper proposed that it is necessary to provide an approach to absorbing the reflected waves on incident boundary. The present approach is described as follows. Firstly, within about half a wavelength distance from the incident boundary, the analytical solutions of incident waves are calculated; secondly, the physical reflected waves or/and spurious ones that are generated by numerical errors are obtained by subtracting the analytical solutions from the numerical ones; in the end, the reflected waves are absorbed by the sponge layer set in the neighborhood of incident boundary. The new approach is validated through an improved numerical model for nonlinear wave propagation in which the reflected waves on the incident boundary are absorbed. Based on the numerical simulation of wave propagation in a water flume with uniform depth and with a submerged shelf, it is shown that the present approach can effectively absorb the reflected waves on the incident boundary.