二维振荡流动中污染云团的收缩*
Contaminant Contraction in Two-dimensional Oscillatory Flows
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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,Dij(t,τ)为剪切扩散导数的方程.一般情况下,∂Dij(t,τ)/∂τ是正的.不存在奇异性.但在转流的初期.记忆函数Dij(t,τ)就有可能是负的.本文给出了Dij和X、Y的解析表示式.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. Dij 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.
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Key words:
- shear dispersion /
- oscillatory flow /
- memory function /
- contaminant contraction
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