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.
出处
《应用数学和力学》
CSCD
北大核心
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
关键词
剪切分散
振荡流动
污染云团
收缩
shear dispersion, oscillatory flow, memory function, conlaminant contraction
