Abstract

Application of grain flow theories to powder lubrication of hydrodynamic bearings requires careful consideration of slip of the flow velocity at the boundaries together with appropriate formulation of the fluctuation (thermal) velocity conditions at the boundaries. Generalized boundary conditions that can be applied to a wide variety of surface and grain material characteristics are developed for a Couette flow configuration. The equations account for both the energy loss at the boundary due to inelastic grain-wall collisions and the energy supplied by the boundary due to collisional momentum supply. The predictions of the model are compared to a number of published results that are based on direct computer simulation of grain-grain collisions. The model’s flexibility is demonstrated by simulating the effects of unequal surface roughnesses.

Issue Section:
Research Papers
Topics:
Flow (Dynamics), Collisions (Physics), Bearings, Boundary-value problems, Computer simulation, Energy dissipation, Lubrication, Momentum
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