A hydrodynamical theory of conservative bounded density currents
A hydrodynamical theory of conservative bounded density currents
复制标题
保守有界密度流的流体动力学理论
DOI：
10.1017/s0022112089000091
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发表时间：
1989
影响因子：
3.7
通讯作者：
D. So
中科院分区：
文献类型：
--
作者：
M. Moncrieff;D. So
本文将Benjamin（1968）对双流体异重流的分析推广到包括异重流内涡量的影响。在恒定的涡度的情况下，密度流的深度被证明是躺在一半和三分之二的通道深度的限制之间。更一般的涡度分布也被认为是，即那些有：（i）在密度流的上部和下部区域的最大值;和（ii）在密度流的中间的最大值。在前者中，在恒定涡度的情况下，密度流结构存在，而在后者中，深翻转环流占主导地位，这可能会导致上游流入的“阻塞”。建立了考虑有限水深和异重流后入流影响的广义传播公式，并考虑了其唯一性问题。分析进一步扩展到一个三流体系统，由物理上不同的组件流，即，密度流，在上层的密度流和上升气流中的流体上升，而不翻转到其流出水平的翻转上升气流区域。两种类型的行为被确定。第一种是对称模式，其中异重流和翻转上升气流具有相同的深度，第二种是非对称模式，其解限制在一定的参数范围内。流体具有相同密度的特殊情况说明了问题的基本动力学以及动量垂直传输的性质。
The Benjamin (1968) analysis of a two-fluid density current is extended to include the effect of vorticity within the current. In the case of constant vorticity, the density-current depth is shown to lie between the limits of half and two-thirds of the channel depth. More general vorticity distributions are also considered, namely those that have: (i) a maximum in the upper and lower regions of the density current; and (ii) a maximum in the middle of the density current. In the former, as in the case of constant vorticity, density-current structures exist, whereas in the latter, deep overturning circulations predominate which can cause a ‘blocking’ of the upstream inflow. A generalized propagation formula which includes the effects of finite depth and rear inflow into the density current is established and the uniqueness issue is considered. The analysis is further extended to a three-fluid system, composed of physically distinct component flows, namely, a density current, an overturning updraught region in upper levels ahead of the density current and an updraught in which the fluid ascends without overturning to its outflow level. Two types of behaviour are identified. First, a symmetric mode in which the density current and the overturning updraught have the same depth and, second, an asymmetric mode with solutions restricted to a certain parameter range. A special case in which the fluids have the same density illustrates the basic dynamics of the problem and also the nature of the vertical transport of momentum.