Vertical mixing due to the breaking of critical internal waves on sloping boundaries
Vertical mixing due to the breaking of critical internal waves on sloping boundaries
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DOI：
10.1017/s0022112089001849
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发表时间：
1989-07
影响因子：
3.7
通讯作者：
G. Ivey;R. Nokes
中科院分区：
文献类型：
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作者：
G. Ivey;R. Nokes
用室内实验方法研究了连续分层流体中内波在倾斜边界上的破裂所引起的垂直混合现象。注意仅限于入射波群速度矢量的斜率等于底斜率的临界波的情况。沿倾斜边界形成湍流底边界层，其厚度取决于入射波幅值。混合效率的定义是由于混合而增加的势能与入射波损失的动能之比，它取决于流动的稳定性，其上限约为0.20。通过考察持续混合所引起的流体势能的增加，我们能够计算不发生混合的耗散εtr的过渡值。对于临界内波在倾斜边界处破碎引起的混合，我们得到εtr =(8±2)νN2。通过与网格湍流实验的比较，这表明，虽然εtr/νN2在现有数据集中= 0(10)，但εtr的具体值可能与机制有关。
A laboratory experiment is used to examine the vertical mixing resulting from the breaking of internal waves on a sloping boundary in a continuously stratified fluid. Attention is confined to the case of critical waves when the slope of the group velocity vector of the incident waves is equal to the bottom slope. Along the sloping boundary a turbulent bottom boundary layer forms with a thickness dependent on the incident wave amplitude. The mixing efficiency, defined as the ratio of the increase in potential energy due to mixing to the loss of kinetic energy by the incident waves, is dependent upon the stability of the flow and has an upper bound of approximately 0.20. By examining the increase in potential energy of the fluid as a result of sustained mixing, we are able to compute the transition value of the dissipation εtr below which no mixing occures. For mixing due to the breaking of critical internal waves on sloping boundaries we find that εtr = (8±2)νN2. From comparisons with experiments with grid-generated turbulence, this suggests that while εtr/νN2 = 0(10) in the available data sets, the specific value of εtr may be mechanism dependent.