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

利用新开发的荧光折射率匹配和颗粒图像测速技术，研究流体对颗粒的侵蚀、沉积和过滤现象。一种以锥形流变仪为模型的新装置将用于在颗粒表面施加均匀剪切，以检查侵蚀的开始和随后在长时间内的稳态侵蚀剖面。运动层内应力-应变关系的测量将允许确定颗粒流体系统的本构关系，其中惯性、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玻璃微珠，以及天然石英颗粒，将获得颗粒摩擦、形状和填充性能的影响。还将进行补充实验，研究流体正常流过颗粒介质表面对侵蚀的影响。这些研究对于通过可渗透沉积层从地下提取碳氢化合物的井中形成泥饼尤为重要。剪切流体的非牛顿性质的影响，如由于剪切稀释剂和胶凝剂的加入，也将进行研究。由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很重要，包括沙丘和河床的动力学、泥浆输送、钻孔中的泥饼堆积以及水力压裂中支撑剂的沉积。尽管已经报道了大量的经验研究，但由于难以在不透明颗粒介质中进行良好的表征测量，因此无法获得可靠的侵蚀规律。该项目将为颗粒介质提供详细的特征数据，这些数据反过来将用于发展本构关系，该本构关系可用于预测颗粒通量作为施加流体应力的函数。该项目由工程理事会化学、生物工程、环境和运输系统部门的颗粒和多相过程部门以及地球科学部的地貌和土地利用动力学（GLD）计划共同资助。

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.