Authors: Gerald Henry Meeten
Publish Date: 2003/11/22
Volume: 43, Issue: 1, Pages: 6-16
Abstract
Newtonian liquids and nonNewtonian soft solids were squeezed between parallel glass plates by a constant force F applied at time t=0 The plate separation ht and the squeezerate V = dot h were measured for different amplitudes of plate roughness in the range 03–31 μm Newtonian liquids obeyed the relation V∝h 3 of Stephan 1874 for large plate separations Departures from this relation that occurred when h approached the roughness amplitude were attributed to radial liquid permeation through the rough region Most nonNewtonian materials showed boundaryslip that varied with roughness amplitude Some showed slip that varied strongly during the squeezing process Perfect slip zero boundary shear stress was not approached by any material even when squeezed by opticallypolished plates If the plates had sufficient roughness amplitude eg about 30 μm boundary slip was practically absent and the dependence of V on h was close to that predicted by noslip theory of a HerschelBulkley fluid in squeeze flow Covey and Stanmore 1981 Adams et al 1994I am grateful to JD Sherwood Schlumberger and WG Griffin University of Cambridge Earth Sciences for useful discussions and to EW Llewellin University of Bristol for unpublished LGS data I am obliged to MC Sheppard Schlumberger for his support
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