Flow classification of radial and squeeze flows between parallel disks

Abstract

The flow classification developed by Thompson and Souza Mendes [Int. J. Engng. Sci. 43 (2005) 79-105] is applied to radial and squeeze flows between two parallel disks. Based on the lubrication approximation, explicit expressions of the flow classification parameter, namely ℛ , could be obtained for those flows, and the results for power-law and Bingham fluids are presented. It is shown that 0 ≤ ℛ ≤ 1 in the radial flow of both power-law and Bingham fluids, which reflects mixed shear and extensional flow. In the squeeze flow of a power-law fluid, the overall distribution of ℛ is similar to the radial flow case. In the squeeze flow of a Bingham fluid, on the other hand, it is noted that there can be a particular region where ℛ > 1 , which is due to the rapid rotation of the principal axes of the rate-of-strain tensor. • Kinematics of radial and squeeze flows is studied using persistence-of-straining. • Flow classification parameter is explicitly computed for radial and squeeze flows. • Results for power-law and Bingham fluids are presented. • The effect of power-law index and yield stress on flow kinematics is discussed.