Thermal instabilities in porous media
Abstract
The permanently unsteady fluctuating natural convective state is described or a fluid which saturates a cube of porous medium with constant temperature top and bottom and insulated vertical sides having an initially linear temperature distribution. Four regimes exist as the Rayleigh number increases. The first regime is the conduction state. The second regime is the steady natural convective state which begins at the Rayleigh number 4 pi(2). The third regime is the permanently unsteady regularly fluctuating convective state which begins at a Rayleigh number between 550 and 600. It is characterized by periodic variations in the Nusselt number with time in which the frequency of the variations increases with increasing Rayleigh numbers. The fourth regime is the permanently unsteady irregularly fluctuating convective state which begins at a Rayleigh number between 625 and 650. It is characterized by random variations in the Nusselt number with time and the range of frequencies increases with increasing Rayleigh numbers.
 Publication:

Ph.D. Thesis
 Pub Date:
 December 1985
 Bibcode:
 1985PhDT........54S
 Keywords:

 Flow Distribution;
 Heat Transfer;
 Porous Materials;
 Thermal Stability;
 Rayleigh Number;
 Temperature Distribution;
 Fluid Mechanics and Heat Transfer