Revisiting Johnson and Jackson boundary conditions for granular flows |
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Authors: | Tingwen Li Sofiane Benyahia |
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Affiliation: | 1. National Energy Technology Laboratory, Department of Energy, Morgantown, WV 26505;2. URS Corporation, Morgantown, WV 26505 |
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Abstract: | In this article, we revisit Johnson and Jackson boundary conditions for granular flows. The oblique collision between a particle and a flat wall is analyzed by adopting the classic rigid‐body theory and a more realistic semianalytical model. Based on the kinetic granular theory, the input parameter for the partial‐slip boundary conditions, specularity coefficient, which is not measurable in experiments, is then interpreted as a function of the particle‐wall restitution coefficient, the frictional coefficient, and the normalized slip velocity at the wall. An analytical expression for the specularity coefficient is suggested for a flat, frictional surface with a low frictional coefficient. The procedure for determining the specularity coefficient for a more general problem is outlined, and a working approximation is provided. Published 2011 American Institute of Chemical Engineers, 2012 |
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Keywords: | granular flow boundary condition two‐fluid model rigid‐body theory specularity coefficient |
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