Numerical analysis of entropy generation in mixed-convection MHD flow in vertical channel

A numerical analysis is performed of the entropy generation within a combined forced and free convective magnetohydrodynamic (MHD) flow in a parallel-plate vertical channel. The MHD flow is assumed to be steady state, laminar and fully developed. The analysis takes account of the effects of both Joule heating and viscous dissipation. The nonlinear governing equations for the velocity and temperature fields are solved using the differential transformation method (D.T.M.). It is shown that the numerical results are in good agreement with the analytical solutions. The numerical values of the velocity and temperature are used to derive the corresponding entropy generation number (N-s) and Bejan number (B-e) within the vertical channel under asymmetric heating conditions. The results show that the minimum entropy generation number and the maximum Bejan number occur near the centerline of the channel. Overall, the results confirm that the differential transformation method provides an accurate and computationally-efficient means of analyzing the nonlinear governing equations of the velocity and temperature fields for MHD flow. (c) 2012 Elsevier Ltd. All rights reserved.