Granular erosion, transport, and dynamic-filtration driven by fluid flow

1335928 PI：Kudroli将使用最新开发的荧光折射率匹配和粒子图像测速技术来研究流体对颗粒的侵蚀、沉积和过滤现象。一种模仿锥形流变仪的新装置将被用来对颗粒表面施加均匀剪切，以检查在较长时间段内的冲刷开始和随后的稳态冲刷剖面。测量移动层内的应力-应变关系将允许确定颗粒-流体系统的本构关系，其中惯性以及重力、摩擦和粘性相互作用是重要的。通过使用各种透明光滑或蚀刻的玻璃微珠和天然石英颗粒，可以获得颗粒摩擦、形状和填充性能的效果。还将进行补充实验，研究流体垂直流过颗粒介质表面对侵蚀的影响。这些研究对于通过用于从地下提取碳氢化合物的可渗透沉积层的钻井中的泥饼形成特别重要。还将研究剪切流体的非牛顿性质的影响，例如由于添加剪切稀释剂和胶凝剂。流体流动引起的颗粒侵蚀、沉积和过滤现象在许多自然和工业过程中都是重要的，包括沙丘和河床的动力学、泥浆输送、钻孔中的泥饼堆积和水力压裂中支撑剂的沉积。虽然已经报道了相当多的经验研究，但由于难以在具有不透明颗粒介质的现场进行表征良好的测量，因此没有可靠的侵蚀规律可用。该项目将提供具有良好特性的颗粒介质的详细数据，这些数据将被用于建立本构关系，这些本构关系可用于预测颗粒通量作为施加流体应力的函数。该项目由工程局化学、生物工程、环境和运输系统司的颗粒和多相过程以及地球科学部的地貌和土地利用动力学(GLD)计划联合资助。

1335928 PI: KudrolliThe phenomena of granular erosion, deposition, and filtration by a fluid flow will be investigated using newly developed fluorescent refractive index matching and particle image velocimetry techniques. A new apparatus modeled after a conical rheometer will be used to apply uniform shear on a granular surface to examine the onset of erosion and subsequent steady state erosion profiles over extended periods of time. The measurement of the stress-strain relation within the moving layer will allow the determination of a constitutive relation for granular-fluid systems in which inertia, along with gravity, friction, and viscous interactions are important. The effect of the particle friction, shape and packing properties will be obtained by using various transparent smooth or etched glass beads, and natural quartz particles. The complementary experiments investigating the effect of fluid flowing normal through the surface of the granular medium on the erosion will also be carried out. These investigations are of particular importance to mud cake formation in bore wells through permeable sedimentary layers used to extract hydrocarbons from the subsurface. The effect of the non-Newtonian nature of the shearing fluid such as due to the addition of shear thinning and gelling agents will be also investigated.The phenomena of granular erosion, deposition, and filtration due to fluid flow are important in many natural and industrial processes including in the dynamics of sand dunes and river beds, slurry transport, mud cake buildup in bore holes, and deposition of proppants in hydraulic fracturing. Although a considerable number of empirical studies have been reported, robust erosion laws are not available because of the difficulty in performing well characterized measurements in the field with opaque granular media. This project will provide detailed data for well characterized granular media which in turn will be used to develop constitutive relations that can be used to predict granular flux as a function of applied fluid stress.The project is jointly funded by the Particulate and Multiphase Processes in the Division of Chemical, Bioengineering, Environmental, and Transport Systems in Engineering Directorate and the Geomorphology and Land Use Dynamics (GLD) Program in the Division of Earth Sciences.