Couette-Poiseuille flow with partial slip and uniform cross flow for power-law fluids

TL;DR

This paper derives exact solutions for steady power-law fluid flow between parallel plates with partial slip and uniform cross flow, revealing flow behaviors and special cases for different fluid types.

Contribution

It provides new exact solutions for power-law fluids with partial slip and cross flow, including special cases and degenerate limits, enhancing understanding of complex flow regimes.

Findings

Exact solutions in closed form for specific power-law indices

Flow type varies with cross flow and pressure gradient

Identification of a failure case for the dilatant fluid model

Abstract

Exact solutions are obtained for the steady flow of a power-law fluid between parallel plates with partial slip conditions and uniform cross flow. The problem is properly formulated and similarities are exploited. The exact solutions are obtained in terms of integrals which can be performed, in closed form, in special cases of the power-law index n. Solutions to cases of n=1/2, 1, and 2; representing a pseudo-plastic, a Newtonian, and a dilatant fluid, respectively, are presented. Tendencies to corresponding degenerate cases in the literature are demonstrated. Depending on the strength of the cross flow and the pressure gradient, the flow may be of Couette type with convex, linear, or concave velocity profile; or of Poiseuille type. Borderline cases are identified. Moreover, a case in which the power-law model for the dilatant fluid fails is detected.