Partial slip boundary conditions for collisional granular flows at flat frictional walls

Conference Dates

May 22-27, 2016


Generally, slip occurs at the boundary wall for the granular flows, and the boundary may provide fluctuation energy to the flow. Wall boundary conditions (BCs) for the solids phase have significant effects on numerical predictions of various gas-solids fluidized beds. In this work, we derive new boundary conditions for collisional granular flows of spheres at flat frictional walls. New theory for the solids stress tensors, energy dissipation rates per unit area and the fluxes of fluctuation energy is proposed distinguishing sliding and sticking collisions and including particle rotation. Comparisons between the theory and the literature simulation data from Louge (1) show that an excellent prediction for stress ratio can be obtained. We propose an approximated expression for the mean rotational velocity in the bubbling fluidized beds using discrete particle model. The theory also predicts better agreement for the fluxes of fluctuation energy and energy dissipation rates for relative rough spheres with the expression. Finally, we determine new BCs with an extra BC for the rotational granular temperature based on the theory within the framework of kinetic theory of granular flow.

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