二维振荡流动中污染云团的收缩  

Contaminant Contraction in Two-dimensional Oscillatory Flows

作　　者：刘宇陆[1] 蔡树棠[2] 

机构地区：[1]上海工业大学 [2]上海市应用数学和力学研究所

出　　处：《应用数学和力学》1993年第11期949-959,共11页Applied Mathematics and Mechanics

基　　金：国家自然科学基金资助项目

摘　　要：当垂向扩散时间尺度与流动的周期相当时,在转流过程中,污染云团将会出现收缩.这时水平剪切分散导数将会出现负值奇性.本文根据作者两维延迟扩散方程:其中(?)(t),(?)(t)为深度平均水平速度.导出X(t,τ),Y(t,τ)坐标位移,D_(ij)(t,τ)为剪切扩散导数的方程.一般情况下,是正的.不存在奇异性.但在转流的初期.记忆函数D_(ij)(t,τ)就有可能是负的.本文给出了D_(ij)和X、Y的解析表示式.If the vertically-mixing time is comparable with that of period of oscillator)' current, the contaminant contraction may occur. The coefficient of shear dispersion is negative (singulurity). According io the two-dimensional delay-diffusion equation derived by the author. where u(O. t;(<) are verticay-averaged velocities, the equations for X(i ,r)t Y( t, T), central displacements, dispersion tensor, had been derived. D,, is positive when r is small. If the r is large, the memory functions may be negative. Also the expressions for and X ,Y had been obtained.

关 键 词：剪切分散 振荡流动 污染云团 收缩 

分 类 号：O357.53[理学—流体力学]