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

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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.