Gravity and Turbidity Currents Interacting with Interfaces of Free Surfaces

当密度较大的流体沿主要水平方向传播到较轻的流体中时，就会形成Meiburg重力流。它们在环境和工程应用中经常遇到。例如，寒冷的河流流入较温暖的湖泊，或冷空气锋传播成较温暖的气团。浊流是一种特殊的重力流，其驱动力来自不同的颗粒负荷，就像多沙河流的外流一样。浊流很难分析，因为它们可能通过沉积或再悬浮与周围的流体和/或沉积物床交换颗粒。从地球物理学的角度来看，浊流--主要是海底雪崩--在全球沉积物循环中发挥着关键作用，是沉积物跨越大陆架进入深海的主要方式。埋藏深、压实的古浊积砂岩也是一类重要的油气藏，也是一种特殊类型金矿的赋存岩石。在环境工程背景下，浊流是导致水库中大部分沉积的原因，从而导致储水能力的丧失。重力和浊流经常与分层流体层之间的有效界面或与自由表面相互作用。由此产生的电流/波相互作用产生了一系列有趣而复杂的现象。例如，当海底滑坡在浅水中形成浊流时，它们与海洋(或湖泊)表面的相互作用可能会导致海啸的产生。为了研究上述类型水流的基本动力学，我们将对浊流与界面和自由面的相互作用进行详细的计算研究。模拟和实验将提供有关这种流动中活跃的各种能量转换机制的信息，这反过来将使我们能够开发简化的理论模型来分析它们。拟议的研究将为从浑浊流、河流羽流、火山碎屑流和粉雪雪崩到海底山体滑坡引发的海啸等范围广泛的颗粒流建立这样的模型。这样，将有利于全球沉积物循环研究和环境危害评估等不同领域。

1067847MeiburgGravity currents form when a denser fluid propagates into a lighter one in a predominantly horizontal direction. They are frequently encountered in environmental and engineering applications. Examples are cold river outflows into a warmer lake, or a cold air front propagating into a warmer air mass. Turbidity currents represent a special class of gravity currents in which the driving force results from differential particle loading, as is the case for a sediment-laden river outflow. Turbidity currents are difficult to analyze, as they may exchange particles with surrounding fluid and/or a sediment bed by deposition or resuspension.In a geophysical context turbidity currents - essentially submarine avalanches - play a crucial role in the global sediment cycle, as the principal means of sediment transport across the continental shelves into the deep oceans. Ancient deposits of turbidite sand, deeply buried and compacted, also form an important class of hydrocarbon reservoirs, and the host rocks for a particular type of gold deposits. In an environmental engineering context, turbidity currents are responsible for much of the sedimentation in reservoirs, with consequent loss of water storage capacity.Frequently, gravity and turbidity currents interact with effective interfaces between stratified fluid layers, or with free surfaces. The resulting current/wave interactions give rise to a host of interesting and complex phenomena. For example, when turbidity currents form in shallow water as a result of submarine landslides, their interaction with the surface of the ocean (or lake) can result in the generation of tsunamis.To investigate the fundamental dynamics of the above types of flows, a detailed computational investigation of turbidity currents interacting with interfaces and free surfaces will be undertaken. The simulations and experiments will provide information about the various energy conversion mechanisms active in such flows, which in turn will allow us to develop simplified theoretical models for their analysis. The proposed research will develop such models for a wide range of particle-laden flows, from turbidity currents, river plumes, pyroclastic flows and powder snow avalanches, to tsunamis generated by submarine landslides. In this way, it will benefit such diverse areas as global sediment cycle research and environmental hazard assessment.