Effect of applying a constant magnetic field on transient natural convection in a square cavity and investigation of heat lines

In this paper، the effect of a magnetic field on transient and laminar natural convection in a square cavity with constant temperature side walls filled with liquid gallium (Pr=0. 02) is investigated numerically. Governing equations are discretized using the control volume method. The results are presented in the form of streamlines، isotherms، heat lines and plots of Nusselt number versus time. The results have shown that with increasing magnetic field strength and therefore the Hartmann number، velocity inside the cavity reduces. Thus maximum absolute value of stream function and the heat transfer between the hot and cold walls of the cavity decreases and the free convection has been weakened. Applying the magnetic field (high enough) suppresses the convection flow and decreases the heat transfer rate and thus conduction heat transfer mechanism become dominant in the cavity.