Irreversibility investigation on MHD natural convection in a square cavity for different Prandtl numbers

Abstract

Irreversibility of MHD fluids in natural convection through a square cavity is numerically investigated. The
cavity is heated and cooled along the active walls whereas the two other walls are adiabatic. Entropy
generation due to heat transfer, fluid friction and an imposed horizontal magnetic field has been determined
for a laminar flow, by solving numerically the conservation equations of continuity, momentum and energy,
using the Control Volume Finite-Element Method. The structure of the studied flows depends on three
dimensionless parameters which are: the Prandtl number, the thermal Grashof number and the Hartmann
number. Results show that the magnetic field parameter (Hartmann number) suppresses the flow and this
leads to a decrease of entropy generation. Temperature decreases with the increase of the magnetic field
parameter. The average Nusselt number increases with the Prandtl number and, in particular, its effect is
more evident for higher values of Hartmann number.