Deduction of slip coefficient in slip and transition regimes from existing cylindrical Couette flow data

Abstract

In this paper, we examine the experimental data of Kuhlthau [A.R. Kuhlthau, Air friction on rapidly moving surfaces, Journal of Applied Physics 20 (1949) 217] on two concentric rotating cylinders with a low pressure gas in the gap. The data are used to deduce the slip coefficient in the slip flow and transition flow regimes (0.04less-than-or-equals, slantKnless-than-or-equals, slant8.3). The obtained values of tangential momentum accommodation coefficient for dry air is 1.13 in the slip regime and 1.70 in the transition regime. These results suggest a dependence of slip coefficient on Knudsen number, Kn. Some comments on velocity profile inversion reported in the literature for such flows and calculation of slip velocity on non-planar surfaces are also made. The results are important because they suggest that the Navier–Stokes equation, with slight correction, can be used for analysis of flow in such high Knudsen number regimes.