On gravity currents driven by constant fluxes of saline and particle-laden fluid in the presence of a uniform flow
On gravity currents driven by constant fluxes of saline and particle-laden fluid in the presence of a uniform flow
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DOI：
10.1017/s002211200500546x
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发表时间：
2005-09-25
影响因子：
3.7
通讯作者：
Huppert, HE
中科院分区：
文献类型：
--
作者：
Hogg, AJ;Hallworth, MA;Huppert, HE
据报道，实验将盐水和含有颗粒的液体持续释放到一个长但相对狭窄的充满淡水的水槽中。稠密的流体迅速扩散到水槽中并从源头流走：运动基本上是二维的。在水槽中没有背景流的情况下，运动是对称的，远离源头。然而，在存在背景流的情况下，上游传播速度减慢，下游速度增加。报告了这种运动的测量结果，并且当由于悬浮沉积物的存在而导致密度过高时，还确定了沉积颗粒的分布。除了这个实验计划之外，还开发了新的运动理论模型。这些基于多层深度平均浅水方程，其中界面阻力和混合过程被明确建模。虽然运动的早期阶段与这些界面现象无关，但随着流动减慢，甚至停止，它们发挥着越来越重要的动力学作用。此外还提出了一种新的积分模型。这并不能解决流动的内部动力学问题，但可以很容易地进行积分，并且无需进行更冗长的数值计算。结果表明，浅层模型和积分模型的预测与实验观测结果非常吻合。
Experiments are reported on the sustained release of saline and particle-laden fluid into a long, but relatively narrow, flume, filled with fresh water. The dense fluid rapidly spread across the flume and flowed away from the source: the motion was then essentially two-dimensional. In the absence of a background flow in the flume, the motion was symmetric, away from the source. However, in the presence of a background flow the upstream speed of propagation was slowed and the downstream speed was increased. Measurements of this motion are reported and, when the excess density was due to the presence of suspended sediment, the distribution of the deposited particles was also determined. Alongside this experimental programme, new theoretical models of the motion were developed. These were based upon multi-layered depth-averaged shallow-water equations, in which the interfacial drag and mixing processes were explicitly modelled. While the early stages of the motion are independent of these interfacial phenomena to leading order, they play an increasingly important dynamical role as the the flow is slowed, or even arrested. In addition a new integral model is proposed. This does not resolve the interior dynamics of the flow, but may be readily integrated and obviates the need for more lengthy numerical calculations. It is shown that the predictions from both the shallow-layer and integral models are in close agreement with the experimental observations.