Lubrication With Micropolar Liquids and Its Application to Short Bearings

Abstract

Microscopic effects, generated by micromotions of particles in suspension in a viscous fluid, drastically change the character of the flow between solid walls. To the modified momentum and continuity equations, an equation of angular (spin) particle momentum is added. A vectorial system of equations is presented, for variable material coefficients. General properties of this system are discussed and differential equations for pressure and velocity field are derived. For constant viscosity and micropolar coefficients across the lubricating film, important simplifications lead to easier workable expressions. Under this assumption, the short bearing performance has been analyzed. The fluid pressure increase (compared to Newtonian flow) is represented by a surface depending on two groups of micropolar parameters; the overall bearing characteristics also exhibit larger values with respect to simple Newtonian lubricants. However, for similar gap geometries, the friction coefficient has lower values. Some formulas, regarding the velocity field, friction stresses and side flow, are general and may be applied to any bearing length-diameter ratio.

Effect of Elasticity on Capillary Compensated Flexible Multi-recess Hydrostatic Journal Bearing Operating with Micropolar Lubricant

“…A number of studies [1][2][3][4][5][6][7][8][9][10] on micropolar lubrication have been reported. Das et al [11] have presented the dynamic characteristics of hydrodynamic journal bearings lubricated with micropolar fluids.…”

Influence of Chemical Reaction and Thermal Radiation on Heat and Mass Transfer for Soret and Dufour's Effects on MHD Mixed Convection Hiemenz Flow of a Micropolar Fluid Embedded in a Porous Medium with Slip

“…The theory of micropolar fluids is expected to provide a mathematical model for the non-Newtonian behavior observed in certain fluids such as liquid crystal, 3 4 low-concentration suspension flow, 5 6 blood rheology, 7-10 the presence of dust or smoke 11 12 the effect of dirt in journal bearing. [13][14][15][16] The hydromagnetic stagnation point flow past heated or cooled bodies have attracted many researchers due to their applications in most of the engineering and natural processes. Examples include plasma studies, blood flow * Author to whom correspondence should be addressed.…”

Effect of Surface Roughness on the Squeeze Film Lubrication of Finite Poroelastic Partial Journal Bearings with Couple Stress Fluids: A Special Reference to Hip Joint Lubrication

“…The hip joint can transmit high dynamic loads (7-8 times body weight) and accommodate a wide range of movements. A number of lubrication theories have been proposed in the literature to account for the low coefficient of friction and low wear observed in healthy joints [4,5]. Normal joints exhibit coefficients of friction of the order of 0.005-0.002 and undergo very little wear or degradation over several decades of use.…”