NUMERICAL COMPUTATION FOR NATURAL CONVECTION OF AIR IN A CUBIC ENCLOSURE UNDER COMBINATION OF MAGNETIZING AND GRAVITATIONAL FORCES

Abstract

Numerical computations were carried out for natural convection of air in a cubic enclosure under both magnetizing and gravitational force fields. The air in the cubic enclosure is heated from one vertical wall and cooled from an opposing cold wall. Two electric wires to produce a magnetic field are located outside the vertical side walls, perpendicular to the hot and cold walls. Computation for a nongravity field revealed that the magnetizing force attracts the cold air and repels the hot air. As a result, convection roll cells can be seen from the top plate, although usual natural-convection roll cells can be seen through a vertical side wall. Computations were carried for the combined force field of gravity and magnetism for the ranges of parameters Pr=0.71, Ra=10 4 , 10 5 , 10 6 , and 10 7 , and n =0, 0.1, 1, and 10, where n represents the strength of magnetic field. As n increases, the effect of the magnetizing force prevails. This can be understood from the model equation and the flow modes computed. As the Rayleigh number increases, the magnetizing force is enhanced also.