Multi-scale soft porous lubrication

This paper reports a comprehensive study of soft lubrication in a porous layer whose thickness ranges from 3.1 mm to 19.0 mm, using two experimental setups for different scales of porous media. We demonstrate that the lubrication theory for soft porous media (Feng and Weinbaum, J. Fluid Mech. 422, 282, 2000) is valid in describing the fluid pressurization, while the theory by Toll (Polym Eng Sci 38, 1337, 1998) is appropriate in predicting the solid phase lifting force. A new model is then developed for estimating the contribution of the fluid pressure to the total lift, which, along with extensive dimensional analysis, provides critical insights for the application of soft porous lubrication in industrial applications.