Entropy generation analysis of radiative heat transfer effects on channel flow of two immiscible couple stress fluids

An analysis is presented to investigate the effects of radiative heat transfer on entropy generation in flow of two immiscible non-Newtonian fluids between two horizontal parallel plates. Both the plates are maintained at constant temperatures higher than that of the fluid. The Stokes’ couple stress flow model is employed. The flow region consists of two zones with the flow of the heavier fluid taking place in the lower zone. The classical “no-slip” condition is prescribed at the plates and continuity of velocity, vorticity, shear stress, couple stress, temperature and heat flux are imposed at the interface. The original partial differential Navier–Stokes equations are converted to ordinary differential equations by assuming velocity and temperature are functions of vertical distance and solved mathematically by usual classical methods. The derived velocity and temperature profiles are used to compute the expressions for the entropy generation number and Bejan number. The effects of relevant parameters on velocity, temperature, entropy generation number and Bejan number are investigated. The computations show that the entropy production decreases with thermal radiation, whereas it increases with viscous dissipation. The effect of viscous dissipation is justified since it significantly affects heat transfer and entropy generation characteristics and therefore should not be ignored.