Lubrication theory

About: Lubrication theory is a research topic. Over the lifetime, 1713 publications have been published within this topic receiving 50261 citations. The topic is also known as: Fluid bearing.

Effect of water temperature on the adhesion between rail and wheel

Abstract: The effects of factors such as rolling speed, contact load, water temperature, and surface roughness on the adhesion coefficient between wheel and rail under wet conditions were investigated theoretically by adopting elasto-hydrodynamic lubrication theory and rough surfaces contact theory [1]. It was found that the water temperature and the surface roughness greatly affect the adhesion performance comparing the other factors. This paper describes an experimental investigation on the effect of water temperature on the adhesion coefficient to verify the significant effect of the water temperature on the adhesion coefficient. The experimental results indicated that a rise in water temperature causes an increase in the adhesion coefficient, which was qualitatively consistent to the numerically calculated results in the previous paper [1].

Numerical simulation of molecularly thin lubricant film flow due to the air bearing slider in hard disk drives

Abstract: In this paper we numerically study the evolution of depletion tracks on molecularly thin lubricant films due to a flying head slider in a hard disk drive. Here the lubricant thickness evolution model is based on continuum thin film lubrication theory with inter-molecular forces. Our numerical simulation involves air bearing pressure, air bearing shear stress, Laplace pressure, the dispersive component of surface free energy and disjoining pressure, a polynomial modeled polar component of surface free energy and disjoining pressure and shear stress caused by the surface free energy gradient. Using these models we perform the lubricant thickness evolution on the disk under a two-rail taper flat slider. The results illustrate the forming process of two depletion tracks of the thin lubricant film on the disk. We also quantify the relative contributions of the various components of the physical models. We find that the polar components of surface free energy and disjoining pressure and the shear stress due to the surface free energy gradient, as well as other physical models, play important rolls in thin lubricant film thickness change.

The Thickness of a Marangoni-Driven Thin Liquid Film Emerging from a Meniscus

Abstract: In this paper, we revisit experiments in which a thin liquid film forms at the tip of a capillary meniscus due to the presence of a thermally induced Marangoni shear stress. Starting from basic fluid mechanical equations, we devise a model for which numerical solutions show that it is able to accurately predict the thickness of the film, in contrast to earlier theories [Fanton, Cazabat, and Quere, it Langmuir, 12 (1996), pp. 5875--5880], where discrepancies with the experimental data of up to 20% were observed. We then find that only a few terms of our model yield a significant contribution to the film thickness. For the resulting reduced model, we derive an approximate, matched asymptotic solution, valid for small capillary numbers, which, to leading order, recovers the result of the older theory. Extending the calculation to the next order yields a correction that substantially improves the accuracy.