The Rayleigh–Bénard convection in near-critical fluids: Influences of the specific heat ratio

Abstract

This article studies the natural convection in near-critical fluids under the Rayleigh–Bénard configuration. The governing equations are non-dimensionalized by using modified scaling factors and five dimensionless parameters are determined, out of which the specific heat ratio γ is investigated thoroughly in terms of its influences on the convection. The governing equations are solved by the finite volume method along with the low Mach number approximation technique. It is revealed that the strength of the piston effect increases with γ. Since the piston effect is more efficient than the convection in terms of heat transfer, as γ is reduced, the relaxation of temperature field is weakened, while the development of convection is enhanced. By comparing the temperature and velocity fields in different cases and analyzing the heat transfer characteristic, we conclude that the final quasi-steady state is almost unaffected.

Acknowledgments

This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.