摘要
本文中,对Lighthill等人有关非均匀介质中波动性质的研究进行了分析。在接近平面波的近似情况,位相并不满足他们提出的连续性原理,而频率随时间的变化成为位相变化的外源。同时沿群速线方向,波数总是守恒的,无论介质均匀与否,但频率在群速方向上总是改变的。这些结果和Lighthill等人的结果是有所差异的。在本文中,除给出了具体的表达式外,并对引起差异的原因作了分析,认为本文结果较为合理。
In this paper, the results on wave propagation in nonuniform media which were studied by Lighthill, Whitham and some others are analysed. It is found that when the phase of wave is expressed as that of near plane wave i. e. θ=k (X, T)x-ω(k(X, T)X, T)t where X, T are ex, et respectively, e is a small parameter, k, a> are local wave number and frequency, then we can get . This means that the phase does not satisfy the principle ofcontinuity as proposed by them. With this result, it is pointed out that the wave number is always constant along the rays while the frequency is variable. This is different from that obtained by Lighthill and others. The causes of these differences are discussed in the paper.
出处
《气象学报》
CSCD
北大核心
1989年第1期1-7,共7页
Acta Meteorologica Sinica
