Lock-release gravity currents and dam-break flows
Lock-release gravity currents and dam-break flows
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DOI：
10.1017/s0022112006002588
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发表时间：
2006-11
影响因子：
3.7
通讯作者：
A. Hogg
中科院分区：
文献类型：
--
作者：
A. Hogg
重力流和溃坝水流是由闸门后最初静止的流体瞬时释放而产生的，理论上采用浅水方程进行建模。通过分析速度图平面内的运动，控制方程变为线性，因此可以从解锁初始条件解析地积分它们。这种方法提供了许多优点：不仅避免了数值计算，而且分析清楚地揭示了后续流动的性质如何取决于水流前部的弗劳德数$\HBox{\it Fr}$。此外，运动还包括均匀波区和简单波区，其中两个特征变量和一个特征变量分别为常量，以及两个特征变量都变化的复杂波区。这些解揭示了以前从未报道过的重力流现象。具体地说，当$\HBox{\it Fr}\，{>；}，2$时，高度场和速度场在晚些时候在水流内的内点变得不连续。相反，当$\HBox{\it Fr}\，{<；}，2$时，有一个沿水流长度传播的波状扰动，在船闸的后壁和水流的前部之间依次反射。
Gravity current and dam-break flows, resulting from the instantaneous release of fluid initially at rest behind a lock gate, are modelled theoretically using the shallow water equations. By analysing the motion in the hodograph plane, the governing equations become linear and hence it is possible to integrate them analytically from lock-release initial conditions. This approach provides many advantages: not only are numerical computations obviated, but the analysis clearly reveals how the nature of the ensuing flow depends on the Froude number, $\hbox{\it Fr}$, at the front of the current. It is also demonstrated that the motion comprises uniform and simple wave regions within which both or one of the characteristic variables are constant, respectively, in addition to complex wave regions within which both characteristic variables vary. These solutions reveal phenomena that have not previously been reported for gravity current flow. Specifically, when $\hbox{\it Fr}\,{>}\,2$, the height and velocity fields become discontinuous at late times at an interior point within the current. Conversely, when $\hbox{\it Fr}\,{<}\,2$, there is a wave-like disturbance that propagates along the length of the current, being reflected successively between the rear wall of the lock and the front of the flow.