一个两流体系统中mKdV孤立波的迎撞*

本文从文2]的基本方程出发,采用约化摄动方法和PLK方法,讨论了三阶非线性和色散效应相平衡的修正的KdV(mKdV)孤立波迎撞问题.这些波在流体密度比等于流体深度比平方的两流体系统界面上传播.我们求得了二阶摄动解,发现在不考虑非均匀相移的情况下,碰撞后孤立波保持原有的形状,这与Fornberg和whitham6]的追撞数值分析结果一致,但当考虑波的非均匀相移后,碰撞后波形将变化.

Head-on Collision between Two mKdV Solitary Waves in a Two-Layer Fluid System

In this paper, based on the equations presented in2], the head-on collision between two solitary waves described by the modified KdV equation (the mKdV equation, for short) is investigated by using thg reductive perturbation method combined with the PLK method. These waves propagate at the interface of a two-fluid system, in which the densiiy ratio of the two fluids equals the square of the depth ratio of the fluids. The second order perturbation solution is obtained.It is found that in the case of disregarding the nonuniform phase shift,the solitary waves preserve their original profiles after collision, which agrees with Fornberg and Whitham's numerical result of overtaking collision6]; whereas after considering the nonuniform phase shift, the wave profiles may deform after collision