Passive scalars in stratified turbulence
Passive scalars in stratified turbulence
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层状湍流中的被动标量
DOI：
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发表时间：
2008
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通讯作者：
E. Lindborg
中科院分区：
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作者：
G. Brethouwer;E. Lindborg
通过数值模拟研究了随机强迫和强分层湍流中具有水平平均梯度的被动标量（或示踪剂）的统计数据。我们观察到在惯性范围内满足无源标量谱的水平各向同性。谱的形式为 Eθ(kh) = CθɛθɛK−1/3kh−5/3，其中 ɛθ、ɛK 分别是标量方差和动能的耗散，Cθ ≃ 0.5 是常数。该光谱与波长 1-500 km 的中尺度范围内的大气测量结果一致。我们还计算了四阶被动标量结构函数，并表明分层湍流中存在间歇效应。
Statistics of a passive scalar (or tracer) with a horizontal mean gradient in randomly forced and strongly stratified turbulence are investigated by numerical simulations. We observe that horizontal isotropy of the passive scalar spectrum is satisfied in the inertial range. The spectrum has the form Eθ(kh) = CθɛθɛK−1/3kh−5/3, where ɛθ, ɛK are the dissipation of scalar variance and kinetic energy respectively, and Cθ ≃ 0.5 is a constant. This spectrum is consistent with atmospheric measurements in the mesoscale range with wavelengths 1–500 km. We also calculate the fourth‐order passive scalar structure function and show that intermittency effects are present in stratified turbulence.