Effects of variable fluid properties and boundary conditions on thermal convection
Abstract
The onset of convection in a fluid layer heated from below is considered. The fluid properties are allowed to vary with temperature according to a linear relation. The fluid layer is bounded by two horizontal rigid plates, and the lower boundary is considered a perfect thermal conductor whereas the upper one is taken with a finite thermal conductivity. With these asymmetric boundary conditions linear variations in density, thermal conductivity and specific heat yield firstorder corrections to the critical value of the Rayleigh number whereas linear variations in viscosity and thermal expansion coefficient give rise to secondorder corrections to the critical Rayleigh number. The greatest effect is due to thermal conductivity variation. When the boundary conditions are symmetric the corrections are secondorder.
 Publication:

International Communications in Heat and Mass Transfer
 Pub Date:
 April 1983
 DOI:
 10.1016/07351933(83)900416
 Bibcode:
 1983ICHMT..10..147C
 Keywords:

 Boundary Conditions;
 Convective Heat Transfer;
 Flow Theory;
 Fluid Boundaries;
 Free Convection;
 Boundary Value Problems;
 Rayleigh Number;
 Thermal Conductivity;
 Thermal Expansion;
 Viscosity;
 Fluid Mechanics and Heat Transfer