RAPID: Modeling and experiments of oil-particulate mixtures of relevance to the Gulf of Mexico oil spill

墨西哥湾石油泄漏可能是美国历史上最严重的环境灾难，美国海岸线的很大一部分受到接近的原油的影响。清理海滩对环境和旅游业都很重要。这个研究项目解决了与清理问题直接相关的油砂动力学的基本问题。这项工作建立在首席研究员最近对斜坡上油砂混合物数学模型的研究基础上，包括油砂混合物分离的临界倾斜角和油/颗粒膜剪切诱导迁移的建模。目前的研究工作解决了一些基本的问题，如是否存在一个导致石油在沙丘中收集或流向沙丘底部的临界倾斜角。波浪剪切周期模式的研究对本研究项目也很重要。油中颗粒（如砂）的动力学是一个复杂的过程，涉及到阻碍沉降动力学和流体动力学（如剪切动力学）。最近，PI的研究小组发现了斜坡上颗粒-油膜混合物的主要物理特性，并且可以定量地解释颗粒沉降到流的下游和清澈流体从流中分离出来之间的分岔。平衡理论比较了由大块流动特性引起的剪切诱导迁移和由重力引起的阻碍沉降，与实验室实验结果吻合较好。目前的研究计划发展了与当前原油泄漏特别相关的斜坡上颗粒-砂混合物的动态理论。除了基本的时变流动问题外，该研究还考虑了油水混合物和周期性时变剪切，例如海滩上的波浪运动和潮汐力可能导致的剪切。

The Gulf of Mexico Oil Spill is perhaps the most significant environmental disaster in US history with a significant portion of the US coastline affected by the approaching crude. Cleanup of beaches is important for both environmental reasons and for the tourist trade. This research program addresses fundamental questions of the dynamics of oil and sand of direct relevance to the cleanup problem. The work builds on recent studies of the Principal Investigator on mathematical models for oil-sand mixtures on slopes, including work on critical inclination angles for separation of oil-sand mixtures and modeling of shear-induced migration in oil/particulate films. The current research effort addresses such basic questions as whether there is a critical angle of incline for beach sand dunes that result in oil collecting in the dune vs. flowing to the bottom of the dune. The study of periodic patterns of shearing due to waves is also important for this research project.The dynamics of particulates (e.g. sand) in oil is a complex process involving hindered settling dynamics and dynamics of the fluid such as shear. Recently the research group of the PI has found the dominant physics for particle-oil film mixtures on an incline and can explain quantitatively the bifurcation that occurs between regimes of particle settling downstream of the flow and clear fluid separating out from the flow. The equilibrium theory compares shear-induced migration due to the bulk flow properties with hindered settling due to gravity, and matches well with laboratory experiments. The current research program develops dynamic theories for particle-sand mixtures on inclines of particular relevance to the current crude oil spill. In addition to basic time-dependent flow problems the study considers oil-water mixtures and periodic time dependent shear such as what might result from wave motion and tidal forces on beaches.