The numerical analysis on the development of Lorentz force and its directional effect on the suppression of buoyancy-driven flow and heat transfer using OpenFOAM

摘要

The development of Lorentz force and its directional effect on the free convection flow and heat transfer in a cube are studied numerically under the influence of a magnetic field using the open source CFD tool kit OpenFOAM. The vertical opposite sidewalls are kept as isothermal while other walls are maintained as insulated. The considered working range of Rayleigh number (Ra) is 10(4), 10(6), and 10(8) at fixed Prandtl number (Pr) of 0.71. The effect of the orientation and intensity of applied magnetic field in the direction normal (B-x) and parallel (B-y) to the isothermal surface are reported. It is noticed that the distribution of electric potential, the nature of the flow of the electric current and the strength of the Lorentz force varies with the intensity of the magnetic field and its orientation. The hydrodynamic and thermal boundary layers get thinner with the increase in Ra, and the Nusselt number increases in natural convection flow cases. The induced Lorentz force significantly suppress the fluid movement and consequently heat transfer. The damping of fluid motion and convective heat transfer are more in case of B-x magnetic field compared to B-y field. The detail discussion on the development of Lorentz force and its strength with the direction in the domain is reported. The temperature distribution and iso-surface shows the significance of applied magnetic field on the mode of heat transfer. (C) 2018 Elsevier Ltd. All rights reserved.