On the dynamics of turbulence near a free surface
On the dynamics of turbulence near a free surface
复制标题
自由表面附近的湍流动力学
DOI：
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发表时间：
2017
影响因子：
3.7
通讯作者：
A. Horner‐Devine
中科院分区：
文献类型：
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作者：
O. Flores;J. Riley;A. Horner‐Devine
我们报告了直接数值模拟，以检查接近平坦无应力表面的湍流的光谱行为。我们发现，与这种自由表面附近的现场测量一致，在无应力表面及其附近的速度的水平分量，在垂直速度远小于水平分量的水平波长下，获得了惯性范围类型的行为。在距无应力表面大约整数长度尺度处，流动已调整回更经典的各向同性湍流。无应力表面附近的湍流行为与最近观察到的强分层流的行为类似，我们认为两种流中这种行为的原因是相同的：抑制大尺度垂直速度和允许水平速度的强垂直剪切，导致能量的小尺度转移和水平速度$-5/3$谱的发展。
We report on direct numerical simulations to examine the spectral behaviour of turbulence close to and at a flat, stress-free surface. We find, consistent with field measurements near such a free surface, that an inertial-range type of behaviour is obtained for the horizontal components of the velocity at and near the stress-free surface, at horizontal wavelengths for which the vertical velocity is much smaller than the horizontal components. At approximately an integral length scale from the stress-free surface, the flow has adjusted back to more classical isotropic turbulence. The behaviour of the turbulence near the stress-free surface is similar to that observed recently for strongly stratified flows, and we argue that the causes of that behaviour are the same in both flows: the suppression of the large-scale vertical velocity and the allowance of strong vertical shearing of the horizontal velocity leading to a downscale transfer of energy and to the development of the $-5/3$ spectra for the horizontal velocities.