A study on entropy generation on thin film flow over an unsteady stretching sheet under the influence of magnetic field, thermocapillarity, thermal radiation and internal heat generation/absorption

Abstract

Entropy generation is inherently affiliated with transport of thermal energy. However, not much attention has been paid to the study of entropy generation in liquid thin film flows. Hence, in this paper an analysis is carried out to study the entropy generation in a thin viscous fluid film on a stretching sheet embedded in a porous medium subject to a magnetic field and thermocapillarity force taking thermal radiation and internal heating/absorption into account. The numerical solution of the equations of momentum and energy governing the flow is obtained. Influence of various parameters emerged in the analysis on the velocity, temperature, surface drag, Nusselt number, entropy generation number and the Bejan number are graphically illustrated and discussed. Thermocapillarity number shows an enhancement of velocity at the free surface. Film thickness is found to increase with increasing thermocapillary force. Thinner films are noticed for stronger magnetic field strengths. It is found that in the absence of thermocapillary force, the effect of magnetic field on entropy generation number near the stretching surface is prominent. Thermocapillarity is seen to have a stronger effect on the entropy generation number near the stretching surface as well as at the free surface.