Analytical solutions for squeeze flow with partial wall slip

Abstract Squeeze flow between parallel plates of a purely viscous material is considered for small gaps both for a Newtonian and power law fluid with partial wall slip. The results for the squeeze force as a function of the squeezing speed reduce to the Stefan and Scott equations in the no slip limit, respectively. The slip velocity at the plate increases linearly with the radius up to the rim slip velocity v s . For small gaps H , the resulting apparent Newtonian rim shear rate—measured for a constant rim shear stress, i.e. an imposed force increasing proportional to 1/ H —yields a straight line if plotted versus 1/ H . The slope of the straight line is equal to 6 v s whereas the intersect with the ordinate yields the effective Newtonian rim shear rate to be converted into the true rim shear rate by means of the power law exponent. The advantage of the new technique is the separation of bulk shear and wall slip from a single test. A more general derivation for the Newtonian case being also valid for full lubrication and large gaps is used to explain the gap dependence of the squeeze modulus of an elastic material.