二维振荡流动中污染云团的收缩<sup>*</sup>

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二维振荡流动中污染云团的收缩^*

基金项目: * 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^[7]: 其中u(t),v (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,∂D_ij(t,τ)/∂τ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.
- 剪切分散理论 /
- 记忆特性 /
- 振荡流动 /
- 污染云团收缩
Abstract: If the vertically-mixing time is comparable with that of period oscillatory current, the contaminant contraction may occur. The coefficient of shear dispersion is negative (singularity). According to the two-dimensional delay-diffusion equation derived by the author^[7]: where u(t),v(t) are vertically-averaged velocities, the equations for X(t,τ), Y(t,τ), central displacement, dispersion tensor, had been derived. D_ij is positive when τ is small. If the is large, the memory functions may be negative. Also the expressions for and X, Y had been obtained.
- shear dispersion /
- oscillatory flow /
- memory function /
- contaminant contraction

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