MIXING EFFICIENCY IN STRATIFIED SHEAR FLOWS
MIXING EFFICIENCY IN STRATIFIED SHEAR FLOWS
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DOI：
10.1146/annurev.fluid.35.101101.161144
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发表时间：
2003-11
影响因子：
27.7
通讯作者：
W. Peltier;Colm‐cille P. Caulfield
中科院分区：
文献类型：
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作者：
W. Peltier;Colm‐cille P. Caulfield
控制稳定分层流体中密度场被湍流过程混合的效率的物理机制问题仍然是个谜。同样令人费解的是对数值~ 0.2的解释，这是实验观察到的这种效率的特征。我们回顾了最近关于分层平行流中的湍流过渡的研究，表明该值不仅在数值上可预测，而且有望成为表征湍流前分层强度的理查德森数的非单调函数。混合效率的这个值似乎是湍流后期行为的特征，在最初的层流剪切流通过开尔文-亥姆霍兹型的中间不稳定性过渡到湍流之后发展起来。
▪ Abstract The issue of the physical mechanism(s) that control the efficiency with which the density field in stably stratified fluid is mixed by turbulent processes has remained enigmatic. Similarly enigmatic has been an explanation of the numerical value of ∼0.2, which is observed to characterize this efficiency experimentally. We review recent work on the turbulence transition in stratified parallel flows that demonstrates that this value is not only numerically predictable but also that it is expected to be a nonmonotonic function of the Richardson number that characterizes preturbulent stratification strength. This value of the mixing efficiency appears to be characteristic of the late-time behavior of the turbulent flow that develops after an initially laminar shear flow has undergone the transition to turbulence through an intermediate instability of Kelvin-Helmholtz type.