Heat transfer characteristics of magnetohydrodynamic electroosmotic flow in a rectangular microchannel

The heat transfer characteristics of incomprehensible magnetohydrodynamic electroosmotic flow through a two-dimensional rectangular microchannel are studied theoretically, and we consider electromagnetic effect under the combined electrokinetic effect by applying a lateral electric field and a vertical magnetic field to existing axial electric field. To maintain the flow, pressure gradient is also provided. The effect of viscous dissipation combined with Joule heating and electromagnetic coupling heat is also taken into consideration under the boundary assumption of uniform wall heat flux. The analytical expression of non-dimensional velocity in rectangular microchannel is obtained, from which non-dimensional temperature and Nusselt number are derived. Through theoretical analysis and numerical calculation, these dimensionless physical quantities are graphically discussed by different parameter values, such as Hartmann number Ha, Brinkman number Br and parameter S (denoting the intensity of the lateral electric field). The results show that the lateral electric field has obvious effect in controlling the flow. Without the applied lateral electric field, the normal velocity gradually decreases with Ha. In the presence of imposed lateral electric field, with the increase of Hartmann number Ha, both the variation profiles of velocity and temperature fields show increasing-decreasing trend, the threshold value is determined by a so-called critical Hartmann number, whereas Nu profile has the adverse trend. Finally, we also discuss the impacts of the viscous dissipation on the thermal transport processes. (C) 2018 Elsevier Masson SAS. All rights reserved.