Melting of ice in a porous medium heated from below

Abstract

A numerical study is made of the melting of ice heated from below in a cavity filled with a porous medium, using the time-dependent form of the governing equations. The natural convection in the liquid phase, the conduction in the subcooled ice region, and the effect of density inversion of water are incorporated into the numerical simulation. The primary characteristics of the melting process, i.e. the onset of convection, the flow pattern in the melt, the heat transfer rate, and the interface position, are studied in terms of the Rayleigh number, the Stefan number, the aspect ratio of the cavity, and the density inversion of water. Principal findings indicate that the initial cellular pattern formed just after the onset of convection passes through several intermediate forms in its transition to a final steady state. Each change in the convection pattern is accompanied by a sudden increase in the heat transfer rate and in the displacement velocity of the solid-liquid interface. A local maximum in the heat transfer rate is exhibited shortly after the establishment of the new convection pattern.