Paper presented at the 5th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, South Africa, 1-4 July, 2007.
Fundamental equations of a compressible viscous heat-conducting fluid are derived. The rigorous linear stability
analysis has been used for the onset of thermal convection and internal gravity waves. Particular emphasis is placed
upon the influence of a thermo-acoustic waves (piston effect) on these phenomena. .This recently found contra-intuitive
speeding up of thermal equilibration at constant volume replaced the traditional slowing down in a strongly compressible
liquid at constant pressure. Our analysis shows that for the onset of convection the results are coincide with those at fixed
pressure proving thereby that the piston effect does not influence the. thermodynamic phenomenon of free convection.
However, the dynamic phenomenon of propagation of the internal gravity waves is essentially dependent on the piston