Visualization and analysis of surface tension and cooling effects on differentially heated cavity using heatline concept

Convection in a square cavity with a free surface and heated from the side is visualized and analyzed by the heatline concept. The temperature gradient is applied along the top free surface and the heat balance at the surface is assumed to obey Newton’s law of cooling. The finite difference method has been used to solve the dimensionless governing equations. The governing parameters considered are the Marangoni number (0 ⩽ Ma ⩽ 1000), the Biot number (0 ⩽ Bi ⩽ 6) and the Prandtl number (0.054 ⩽ Pr ⩽ 6.2). The flows of heat and fluid are of a similar type except at a strong cooling condition. The heat transfer performance presents a minimum at Marangoni number of roughly 100, 200 and 600 for the cavity filled with liquid metal, mixture of noble gases and air, respectively.