Topic
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.
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TL;DR: In this paper, the Stokes flow of micro-polar fluids by peristaltic pumping through the cylindrical tube under the effect of the slip boundary condition was studied.
Abstract: This paper studies the Stokes flow of micro-polar fluids by peristaltic pumping through the cylindrical tube under the effect of the slip boundary condition. The motion of the wall is governed by the sinusoidal wave equation. The analytical and numerical solutions for the axial velocity, the micro-polar vector, the stream function, the pressure gradient, the friction force, and the mechanical efficiency are obtained by using the lubrication theory under the low Reynolds number and long wavelength approximations. The impacts of the emerging parameters, such as the coupling number, the micro-polar parameter, the slip parameter on pumping characteristics, the friction force, the velocity profile, the mechanical efficiency, and the trapping phenomenon are depicted graphically. The numerical results infer that large pressure is required for peristaltic pumping when the coupling number is large, while opposite behaviors are found for the micro-polar parameter and the slip parameter. The size of the trapped bolus reduces with the increase in the coupling number and the micro-polar parameter, whereas it blows up with the increase in the slip parameter.
9 citations
TL;DR: In this paper, a system of two coupled nonlinear hyperbolic equations for the evolution of the two interfaces between clear fluid, suspension and sediment is proposed, and solved for batch settling and the filling of a channel that initially contains clear fluid.
Abstract: Settling of a dilute, monodisperse suspension between two inclined, narrowly spaced parallel plates is considered. Effects of sediment motion are accounted for. Lubrication theory and a simplified model for the particle motion lead to a system of two coupled nonlinear hyperbolic equations for the evolution of the two interfaces between clear fluid, suspension and sediment. Two problems are solved: batch settling and the filling of a channel that initially contains clear fluid. In the batch-settling case, the sediment has no major qualitative effect on the motion. In the filling problem, however, effects of sediment are important.
9 citations
TL;DR: In this article, the leveling of a thin-liquid film on a substrate having a mesa-like feature is analyzed by finite element analysis and lubrication theory applied to the free surface viscous flow problem.
Abstract: The leveling of a thin‐liquid film on a substrate having a mesa‐like feature is analyzed by finite element analysis and lubrication theory applied to the free‐surface viscous flow problem. The height of the mesa is on the order of 1 μm and has a width on the order of 100 μm; the thin‐liquid film is initially conformal to the substrate and has a thickness on the order of 1 μm. Capillarity is found to be the primary driving force for flow. The predicted leveling times from the numerical simulations compare favorably with an analytical solution developed from lubrication theory for the leveling of a thin film on a smooth substrate.
9 citations
TL;DR: A simplified application of the principle of least action provides a useful approximate model of cutting as discussed by the authors, and there is strong evidence that this length is itself determined principally by the adhesional conditions at the interfaces.
Abstract: Metal cutting has several unique features that distinguish it from metal forming and from plain sliding. Extensive new surface is generated in immediate contact with the tool, so that contact with any liquid lubricant does not occur until the sliding process has been completed. The sliding speed is usually very high and the time of transit very short, typically 1 ms or less. It is consequently widely believed that boundary friction and lubrication theory is quite inapplicable to metal cutting, and even less so to grinding. Nevertheless, important analogies can he drawn, and lead to useful practical conclusions. A simplified application of the principle of least action provides a useful approximate model of cutting. Direct experiments confirm that the length of contact on the rake face is a dominant factor, and there is strong evidence that this length is itself determined principally by the adhesional conditions at the interfaces. The reduction of rake-face contact by lubricants has been examined...
9 citations
TL;DR: In this paper, a theory of grease lubrication for cylindrical roller bearing has been deduced, considering the grease as a Bingham plastic, and the special core formation in grease film, the frictional resistance of rolling bearing, the pressure distribution and the load capacity of grease film entrapped between roller and race of cylinder roller bearing have been investigated.
Abstract: The lubrication theory on the substances of rheological behaviour as grease is a recent theme. In particular, as the grease is often used for the lubrication of rolling bearing, it is important to establish a theory of grease lubrication for rolling bearings. In this paper, considering the grease as a Bingham plastic, a theory of grease lubrication for cylindrical roller bearing has been deduced. That is, the special core formation in grease film, the frictional resistance of rolling bearing, the pressure distribution and the load capacity of grease film entrapped between roller and race of cylindrical roller bearing have been researched. In addition, the above grease lubrication theory is compared with the oil lubrication theory.
9 citations