Thermodynamic Analysis of Unsteady Mhd Boundary Layer Flow With Slip Over a Permeable Surface

Abstract

Magnetohydrodynamics (MHD) boundary layer flow problems have become important in industrial manufacturing processes such as plasma studies, chemical engineering, electrochemistry, polymer processing, petroleum industries, MHD power generator cooling of nuclear reactors, and boundary layer control in aerodynamics. Moreover, permeable surfaces are used for boundary layer control in the filtration processes, and also for a heated body to keep its temperature constant. Suction can be utilized on biological chemical processes to remove reactants while blowing is applied to add reactants in the process and to cool the surface body by its ability to decrease the heat transfer rate. In this thesis, both first and second laws of thermodynamics are employed to investigate the inherent irreversibility in an unsteady hydromagnetic, mixed convective boundary layer flow of an electrically conducting, optically dense fluid, over a permeable vertical surface under the combined influence of thermal radiation, velocity slip, temperature jump, buoyancy force, viscous dissipation, Joule heating and magnetic field. The time-dependent governing partial differential equations are reduced to ordinary differential equations by using appropriate similarity variables. A local similarity solution is obtained numerically using the shooting technique coupled with a fourth order Runge-Kutta Fehlberg integration method. The influence of various thermophysical parameters on velocity and temperature profiles, skin friction, Nusselt number, entropy generation rate and Bejan number, are presented graphically and discussed quantitatively. It is found that velocity slip, surface injection, and temperature jump can successfully reduce entropy generation rate in the presence of an applied magnetic field.