Inherent irreversibility and thermal stability for steady flow of variable viscosity liquid film in a cylindrical pipe with convective cooling at the surface

Abstract

Purpose – The purpose of this paper is to investigate the inherent irreversibility and thermal stability in the flow of a variable viscosity fluid through a cylindrical pipe with convective cooling at the surface. Design/methodology/approach – The non-linear momentum and energy equations governing the flow are solved analytically using a perturbation method coupled with a special type of Hermite-Pade´ approximation technique implemented numerically on MAPLE. Findings – Expressions for dimensionless velocity and temperature, thermal criticality conditions and entropy generation number are obtained. A decrease in the fluid viscosity enhances both entropy generation rate and the dominant effect of heat transfer irreversibility near the wall Originality/value – This paper presents the application of the second law of thermodynamics and a special type of Hermite-Pade´ approximation technique to variable viscosity cylindrical pipe flow with convective cooling at the wall.