Onset of Salt-Finger Convection in Anisotropic and Inhomogeneous Porous Media
Resource
International Journal of Heat and Mass Transfer, v.35 n.12, p.3451-3464
Journal
International Journal of Heat and Mass Transfer
Journal Volume
v.35 n.12
Pages
3451-3464
Date Issued
1992
Date
1992
Author(s)
Abstract
In the experiment of directional solidification of binary solutions, the salt-finger convection is usually found to occur prior to the onset of plume convection. The plume containing cold solute-rich liquid is ejected from the dendritic mushy zone, an anisotropic and inhomogeneous porous medium. The salt-finger convection is accordingly believed to be responsible for the formation of plume convection. In this paper, we seek the relation between the onset of salt-finger and plume convection in the mushy zone by a linear stability analysis. We begin with a general study on the influences of the anisotropic and inhomogeneous permeability, thermal diffusivity, and solute diffusivity on the stability characteristics of salt-finger convection in the porous medium. Based on the results obtained, we consider the salt-finger instability in a real dendritic mushy zone identified from the experiment and find that the onset solute Rayleigh number Rsmc of salt-finger convection is invariably much larger than that of plume convection. It is therefore our belief that there is no salt-finger convection in the mush when the plume is initially ejected from the mush. © 1992.
Other Subjects
Porous materials; Solidification; Solutions; Stability; Thermal diffusion; Binary solutions; Directional solidification; Mushy zone; Plume convection; Salt-finger convection; Heat convection
Type
journal article