Concentration Fluctuations in Turbulent Diffusion
Concentration Fluctuations in Turbulent Diffusion
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湍流扩散中的浓度波动
DOI：
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发表时间：
1967
期刊：
影响因子：
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通讯作者：
G. Csanady
中科院分区：
文献类型：
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作者：
G. Csanady
本文从湍流扩散中均方浓度涨落的连续性方程出发，导出了一个守恒律。这一定律的各项与湍流混合层或边界层的能量平衡中的各项非常相似。本文通过下列假设得到了均匀湍流场中连续羽流中MSF的封闭方程：a）浓度通量和MSF通量都可以表示为交换系数乘以梯度，B）对于给定的羽流截面，这两个交换系数相等且为常数，尽管它们随离源的距离而变化; c）MSF的耗散率与局部MSF成比例，并且比例常数，即“衰减时间尺度”，对于给定的截面也是恒定的（即使它是距离的函数）。自相似配置文件的msf被发现是可能的，只要衰变时间尺度与距离源成反比。
Abstract A conservation law is derived from the equation of continuity for the mean-square concentration fluctuations (msf) in turbulent diffusion. The terms of this law are very similar to those found in the energy balance of a turbulent mixing layer or boundary layer. A closed equation for the msf in a continuous plume in a uniform field of turbulence is obtained by the following assumptions: a) that the flux of both concentration and msf may be expressed as an exchange coefficient times gradient; b) that the two exchange coefficients involved are equal and constant for a given cross section of the plume, although they vary with distance from the source; c) and that the dissipation rate of msf is proportional to the local msf and that the constant of proportionality, a “decay-time scale,” is also constant for a given section (even though it is a function of distance). Self-similar profiles of msf are found to be possible, provided that the decay-time scale varies inversely with distance from the source....