Abstract

Dam-break flows are not only an important practical problem in civil and hydraulic engineering, but also a fundamental problem of fluid mechanics. Due to property damage and the loss of numerous lives, it is critically important to have an exhaustive understanding of the landslide dam-break flow and sedimentation. The main objective of this study is a detailed analysis of the mechanisms of dam-breaking flows through physical and theoretical modeling. Our experimental work was focused on the initial stages of dam-break flow in the water channel, where a thin plate separating water at different levels is impulsively withdrawn in the vertical direction upwards, and as a result, a hydrodynamic bore is formed. The theoretical model of the dam-break flow is based on Benney’s shallow water equations. We separately studied the regimes of a breaking and non-breaking bore front. On the hydrodynamic bore, the laws of conservation of mass, momentum, and energy were required in contrast to the classical solutions of Ritter and Stoker, in which the conservation of energy law was not considered at all. The non-breaking flow includes several zones: a shock wave and a shear vorticity flow after it, a contact surface and a continuous discharge zone. The bore in our solution moves faster than the classical bore, which, in turn, propagates faster than the contact surface. The breaking bore is characterized by the generation of a “mushroom-jet” structure, including a pair of vortices, oppositely directed, and a forerunner formed by the plunging jet directed forward. We found that the forerunner of the breaking bore has a speed significantly higher than the speed of the bore. The experiments carried out in the wave flume of the Tainan Hydraulics Laboratory confirmed the theoretical predictions of the proposed dam breaking flow model for various initial conditions.

中文翻译：

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溃坝洪水中洪水传播与先驱现象的实验与理论研究。

摘要

溃坝流量不仅是土木和水利工程中的重要现实问题，还是流体力学的基本问题。由于财产损失和无数生命的丧失，对滑坡溃坝的水流和沉积物有详尽的了解至关重要。这项研究的主要目的是通过物理和理论建模来详细分析溃坝流的机理。我们的实验工作集中在水道溃坝水流的初始阶段，在该水坝中，沿垂直方向向上冲动抽出分离不同水位的薄板，从而形成了水力钻孔。溃坝水流的理论模型基于本尼的浅水方程。我们分别研究了开裂和不开裂的井眼状况。在流体动力学孔上，与经典的解决方案里特和斯托克相反，根本不需要考虑能量守恒定律，因此需要质量，动量和能量守恒定律。不间断流包括几个区域：冲击波和其后的剪切涡流，接触面和连续排出区域。我们解决方案中的孔运动快于传统孔，后者又比接触面传播快。破碎孔的特征在于产生了“蘑菇状喷射”结构，该结构包括一对相反指向的涡流，以及由朝前插入的喷射流形成的先驱体。我们发现，破孔的先行者的速度明显高于破孔的速度。在台南水利实验室波浪槽中进行的实验证实了在各种初始条件下拟建的溃坝水流模型的理论预测。