Solidification of a superheated fluid in a porous medium: effects of convection

Abstract

The solidification of a superheated fluid‐porous medium contained in a rectangular cavity is studied numerically. The bottom and side walls of the cavity are insulated while the top wall is maintained at a constant temperature below the freezing point of the saturating fluid. The study is focused on the effects of superheat on the development of natural convection and heat transfer during the solidification process. For a fluid initially at a temperature above the freezing point, the results obtained by neglecting convection overpredicts the solidification time by about 12 percent for a Rayleigh number of 800. When convection is taken into account, it is found that the solidification process consists of three distinct regimes: the conduction regime, convection regime and the solidification of the remaining fluid that can be described by the Neumann solution for the solidification of a fluid at its freezing point. The numerical simulations are based on the Darcy‐Boussinesq equations, using the front tracking method in a transformed coordinate system. The entire solidification process is described in terms of the evolutions of the streamlines and isotherm patterns, the maximum and average temperatures of the fluid, the interface position, and the heat transfer rate. The parametric domain covered by these simulations is 0 ≤ Ra ≤ 800, 0 ≤ St^l ≤ 0.67, St^s = 0.3 and XL = 1 where Ra is the Rayleigh number, St^l the liquid Stefan number, St^s the solid Stefan number, and XL the aspect ratio of the cavity.

Citation

Zhang, X. and Hung Nguyen, T. (1999), "Solidification of a superheated fluid in a porous medium: effects of convection", International Journal of Numerical Methods for Heat & Fluid Flow, Vol. 9 No. 1, pp. 72-91. https://doi.org/10.1108/09615539910251112