Numerical Modeling and Simulation of a Poroelastic Journal Bearing Lubricated By Nanofluids with Couple-Stresses

Abstract

In this paper we present a numerical simulation of a porous journal bearing considering the fluid film – poroelastic matrix interaction and the non-Newtonian rheological behavior of nanolubricant consisting of base fluid and nanoparticles (NPs). The flow of nanolubricant in the bearing clearance space is described by the Vijay Kumar Stokes micro-continuum theory which considers the characteristic size of nanoparticles such as fullerenes dispersed in a base oil. The flow of the nanolubricant in the porous medium is modeled by the modified Darcy’s law where the Beavers–Joseph slip conditions are applied at the fluid film-porous matrix interface. The deformation of the fluid-film porous matrix interface due to hydrodynamic pressure is calculated by using a simplified analytical thin elastic liner model. The hydrodynamic behavior of lubricating film is governed by the modified Reynolds equation obtained from the momentum, moment of momentum, and mass conservation laws using the classical Reynolds derivation process. The bearing porosity is introduced into the governing modified Reynolds equation by means of the Morgan-Cameron approximation. The steady-state analysis shows that for an imposed operating eccentricity, the load capacity increases with the characteristic size and the concentration of NPs while the attitude angle, the leakage flow rate, and the coefficient of friction decrease. On the other hand, the permeability decreases the hydrodynamic pressure, the load capacity, and the leakage flow rate, and increases the attitude angle and the coefficient of friction.