波状水跃和波状涌潮的分析

Analyses of Undular Hydraulic Jump and Undular Bore

推导了涌潮中尺度方程,并利用此方程,分析水跃和涌潮的性质.对于水跃和涌潮,色散与耗散两种效应强弱的比值依赖干Froude数的函数.存在着两个临界值,当跃前Froude数大于第一个临界值时,水跃和涌潮从单调形态转化为波动形态,随后,波陡随Froude数增大.当Froude数大于第二个临界值时,自由表面破碎,波状涌潮转化为强涌潮.对于涌潮,绝对流速.即落潮流速,对色散波的周期,波长与振幅也有影响.数值计算的结果与水槽试验数据做了对比.说明中尺度模型是研究涌潮发展过程,破碎条件等问题的重要工具.

The mid-scale equations of bores are deduced, and used to analyze the properties of bores and hy-draulic jumps. It is concluded that the effects of dispersion and dissipation of bores depend on the Froude num-ber. There are two critical values. When the Froude number before jump is greater than the first critical value, hydraulic and bore transform from monotonous pattern into undular pattern. then the steepness increases as theFroude number does. When the Froude number is greater than the second critical value, the free surface is bro-ken, and undular bore is changed into strong bore. For the bore, absolute velocity, namely ebb velocity, has some influence on the period , length and amplitude of dispersive wave.Numerical experimental results, being compared with the data of water flume experiment,show that mid-scale model is an important tool to invesigate the evolution of bore and the condition of its breaking, etc.