Heat transfer and entropy generation in viscous-joule heating MHD microchannels flow under asymmetric heating

PurposeThis paper aims to present a numerical investigation into heat transfer and entropy generation resulting from magnetohydrodynamic laminar flow through a microchannel under asymmetric boundary conditions. Furthermore, the authors consider the effects of viscous dissipation and Joule heating.Design/methodology/approachThe finite difference method is used to obtain the numerical solution. Simulations are conducted across a broad range of Hartmann (Ha = 0 similar to 40) and Brinkman (Br = 0.01 similar to 1) numbers, along with various asymmetric isothermal boundaries characterized by a heating ratio denoted as phi.FindingsThe findings indicate a significant increase in the Nusselt number with increasing Hartmann number, regardless of whether Br equals zero or not. In addition, it is demonstrated that temperature differences between the microchannel walls can lead to substantial distortions in fluid temperature distribution and heat transfer. The results reveal that the maximum entropy generation occurs at the highest values of Ha and eta (a dimensionless parameter emerging from the formulation) obtained for phi = -1. Moreover, it is observed that local entropy generation rates are highest near the channel wall at the entrance region.Originality/valueThe study provides valuable insights into the complex interactions between magnetic fields, viscous dissipation and Joule heating in microchannel flows, particularly under asymmetric heating conditions. This contributes to a better understanding of heat transfer and entropy generation in advanced microfluidic systems, which is essential for optimizing their design and performance.