Parametric Study of Natural Convection inside a Partitioned Cavity in the Presence of a Magnetic Field
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Journal of Engineering Physics and Thermophysics, Vol. 93, No. 5, September, 2020
PARAMETRIC STUDY OF NATURAL CONVECTION INSIDE A PARTITIONED CAVITY IN THE PRESENCE OF A MAGNETIC FIELD M. Pirmohammadia and A. Salehi-Shabestarib
UDC 536.25
Steady laminar natural convection flow is studied numerically. The flow domain is a differentially heated square cavity with two partitions that is exposed to a constant horizontal magnetic field. A finite volume-based code is developed by the SIMPLER algorithm. A parametric study is carried out, using different values of the Rayleigh numbers, partition positions, partition heights, and the Hartmann numbers (from zero to 200). It is found that the Nusselt number is an increasing function of the Rayleigh number, but a decreasing function of the partition height and Hartmann number. The position of the partitions affects the streamlines and isotherms, but has a minimal effect on the mean Nusselt number. In addition, the results show that for low partition heights convective heat transfer in a cavity is significant, the braking effect of the Lorentz force is more pronounced, and the mean Nusselt number decreases considerably with increasing magnetic field strength. Keywords: magnetic field, natural convection, partitioned cavity. Introduction. Numerical simulation of natural convective heat transfer and fluid flow in cavities has been carried out extensively for various boundary conditions. This problem has wide application, especially in cooling of electronic components, solar collector–receivers, chemical catalytic reactors, insulation and flooding protection for buried pipes used for district heating and cooling, etc. One of the important factors affecting natural convection is the enclosure geometry. Because of this, the effect of the enclosure geometry on natural convection has been investigated in various researches [1–6]. In some applications, natural convection becomes an undesirable phenomenon (as in material solidification); in such a situation, the process can be controlled by an external magnetic field. Garandet, Alboussiere, and Moreau proposed an analytical solution to the governing equations of magnetohydrodynamics to model the effect of a transverse magnetic field on natural convection in a two-dimensional enclosure [7]. Rudraiah et al. numerically investigated the effect of a transverse magnetic field on a natural convective flow inside a rectangular cavity with isothermal vertical and adiabatic horizontal walls and found that a circulating flow is formed with a relatively weak magnetic field [8]. They found that an increase in the applied magnetic field strength leads to the suppression of convection and the decrease in the rate of convective heat transfer. Al-Najem, Khanafer, and El-Refaee used the approach based on the power-law control volume to determine the flow and temperature fields under a transverse magnetic field in a tilted square enclosure with isothermal vertical and adiabatic horizontal walls at the Prandtl number equal to 0.71 [9]. They showed that
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