Essink Martin H, Pandey Anupam, Karpitschka Stefan, Venner Cornelis H, Snoeijer Jacco H
Physics of Fluids Group, Faculty of Science and Technology, Mesa+ Institute, University of Twente, 7500 AE Enschede, The Netherlands.
Department of Biological and Environmental Engineering, Cornell University, Ithaca, NY 14853, USA.
J Fluid Mech. 2021 Mar 15;915. doi: 10.1017/jfm.2021.96. eCollection 2021 May 25.
Elastohydrodynamic lubrication, or simply soft lubrication, refers to the motion of deformable objects near a boundary lubricated by a fluid, and is one of the key physical mechanisms to minimise friction and wear in natural and engineered systems. Hence it is of particular interest to relate the thickness of the lubricant layer to the entrainment (sliding/rolling) velocity, the mechanical loading exerted onto the contacting elements, and properties of the elastic boundary. In this work we provide an overview of the various regimes of soft lubrication for two-dimensional cylinders in lubricated contact with compliant walls. We discuss the limits of small and large entrainment velocity, which is equivalent to large and small elastic deformations, as the cylinder moves near thick or thin elastic layers. The analysis focusses on thin elastic coatings, both compressible and incompressible, for which analytical scaling laws are not yet available in the regime of large deformations. By analysing the elastohydrodynamic boundary layers that appear at the edge of the contact, we establish the missing scaling laws - including prefactors. As such, we offer a rather complete overview of physically relevant limits of soft lubrication.
弹性流体动力润滑，或简称为软润滑，是指可变形物体在由流体润滑的边界附近的运动，是使自然系统和工程系统中的摩擦和磨损最小化的关键物理机制之一。因此，将润滑层的厚度与夹带（滑动/滚动）速度、施加在接触元件上的机械载荷以及弹性边界的特性联系起来就特别有意义。在这项工作中，我们概述了二维圆柱体与柔顺壁面润滑接触时软润滑的各种状态。我们讨论了小和大夹带速度的极限情况，这相当于圆柱体在靠近厚或薄弹性层移动时的大或小弹性变形。分析聚焦于可压缩和不可压缩的薄弹性涂层，在大变形状态下，对于这些涂层尚无解析标度律。通过分析出现在接触边缘的弹性流体动力边界层，我们建立了缺失的标度律——包括前置因子。这样，我们提供了一个关于软润滑物理相关极限的相当完整的概述。
