Entropy Analysis for MHD Generalised Couette Flow in a Composite Duct

Paresh Vyas,Ashutosh Ranjan

doi:10.1155/2015/895046

Abstract

This paper presents entropy analysis of electrically conducting Newtonian fluid flow inside a horizontal composite duct. The upper impermeable wall of the duct moves with a uniform velocity while the lower wall is porous strata of finite thickness with impermeable bottom. The upper wall and the impermeable bottom are at constant temperature but at different temperatures. The duct is divided into two regions: Region I of clear fluid and Region II of fluid saturated porous layer. Momentum and thermal regimes for clear and porous regions are matched at clear fluid-porous interface by employing suitable matching conditions. The governing equations are solved analytically. Analytical solutions obtained for velocity and temperature are utilized to compute entropy generation. The effects of pertinent parameter on temperature distribution, entropy generation, and Bejan number are portrayed graphically and discussed.

Highlights

All real processes are irreversible, and a physical quantity termed entropy defined in the second law of thermodynamics is a pertinent measure of irreversibility of the systems
Bejan has shown in his pioneer works [1,2,3] that in convective heat transfer processes one can identify parameters which are decisive in entropy generation
It is clear from (24)-(25) that various sources contribute in entropy generation: the first term in these equations shows the contribution of heat transfer to the entropy generation, the second term is the local entropy generation due to fluid friction, and the third term signifies the effect of magnetic field in the generation of entropy

Summary

Introduction

All real processes are irreversible, and a physical quantity termed entropy defined in the second law of thermodynamics is a pertinent measure of irreversibility of the systems. In the present scenario where energy optimization is a natural want there is much scope for devising optimal industrial thermal systems following second law analysis Such analysis helps peep into minimization of entropy by identifying and selecting the parameters to eradicate the erosion of available energy for direct conversion to work. Makinde and Aziz [12] performed analytical and numerical analysis of the second law of thermodynamics for plane Poiseuille flow with asymmetric convective heat transfer taking variable fluid viscosity. Much insight into the issue can be seen in [26,27,28,29] and the references contained therein In this backdrop, entropy generation analysis for MHD laminar Newtonian fluid flow and heat transfer in a composite duct is an interesting situation to look into

Formulation of the Problem

Solution

Second Law Analysis

Results and Discussions

Conclusion