The effect of nonvertical shear on turbulence in a stably stratified medium
The effect of nonvertical shear on turbulence in a stably stratified medium
复制标题
非垂直剪切对稳定分层介质中湍流的影响
DOI：
10.1063/1.869640
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发表时间：
1998
影响因子：
4.6
通讯作者：
S. Sarkar
中科院分区：
文献类型：
--
作者：
F. Jacobitz;S. Sarkar
为了研究非垂直剪切作用下稳定分层流体中湍流的演化，进行了直接数值模拟。以往的研究主要集中在垂直剪切流方面，而本研究首次系统地研究了剪切流的垂直和水平分量。这项工作的主要目的是研究分层方向与平均流向速度梯度之间的夹角θ从θ=0（对应于已充分研究的纯垂直剪切情况）到θ=π/2（对应于纯水平剪切情况）的变化所产生的影响。据观察，湍流动能K在初始阶段之后近似指数地演变。湍流动能K的指数增长率γ随倾斜角θ的增大而非线性增大，且随倾斜角θ的增大而增大。增长率的增加是由于强烈增加的湍流产生引起的。
Direct numerical simulations were performed in order to investigate the evolution of turbulence in a stably stratified fluid forced by nonvertical shear. Past research has been focused on vertical shear flow, and the present work is the first systematic study with vertical and horizontal components of shear. The primary objective of this work was to study the effects of a variation of the angle θ between the direction of stratification and the gradient of the mean streamwise velocity from θ=0, corresponding to the well-studied case of purely vertical shear, to θ=π/2, corresponding to purely horizontal shear. It was observed that the turbulent kinetic energy K evolves approximately exponentially after an initial phase. The exponential growth rate γ of the turbulent kinetic energy K was found to increase nonlinearly, with a strong increase for small deviations from the vertical, when the inclination angle θ was increased. The increased growth rate is due to a strongly increased turbulence production caused ...