Bifurcation and stability analyses for a two-phase Rayleigh-Benard problem in a cavity

Stability and bifurcation analyses of a partially melted or solidified material heated from below and cooled from above in a cavity, the so-called two-phase Rayleigh-Benard problem, are conducted by a finite-volume/Newton's method. Bifurcation analysis techniques using a numerical Jacobian and an iterative matrix solver suitable to this large complicated system are adopted. The onset and evolution of melt flows coupling with the heat conduction in the solid and a deformable melt/solid interface are illustrated through detailed bifurcation diagrams, and the linear stability of each flow family is carefully examined. Some comparison with the one-phase system is performed. Results are presented for a variety of parameters of interest, including the Rayleigh number, aspect ratio, and tilt angle. Although most calculations are presented for the melt with a Prandtl number of one, the effects of Prandtl number on the onset of cellular convection and the sensitivity of symmetry breaking by tilting are examined. Furthermore, the dynamic responses of an unstable static state to stable solutions after small disturbances are illustrated, and the effect of heat of fusion is discussed. (C) 1998 American Institute of Physics.