Hybrid molecular-scale and continuum modeling of two-dimensional flow between inhomogeneous solid surfaces and its application to the thrust bearing.

Context: The flow equations are derived for describing the two-dimensional hybrid molecular-scale and continuum flows in the very small surface separation with inhomogeneous solid surfaces and they can be applied for designing the specific bearings. The aim of the present study is to solve this specific flow problem in engineering with normal computational cost. The flow factor approach model describes the flow of the molecule layer adjacent to the solid surface and the Newtonian fluid model describes the flow of the intermediate continuum fluid. By using these flow equations, the simulation results show that designing the inhomogeneous stationary surface can very significantly improve the load-carrying capacity of the hydrodynamic thrust bearing with low clearances.

Method: The flow of the physically adsorbed layer is treated as non-continuum and it is modeled by the equivalent non-continuum flow model by considering the fluid molecules orientated normal to the solid surface. The fluid between the two adsorbed layers is treated as continuum and Newtonian. The slippage can occur between the adsorbed layer-solid surface interface. It is assumed as absent on the adsorbed layer-continuum fluid interface. The flow equations are derived according to the equilibrium of the momentum transfer in the surface clearance. The film pressures and carried load of the thrust bearing with low clearance and inhomogeneous surfaces are derived by applying the obtained flow equations.