Numerical study of Rayleigh-Béenard convection in a supercritical fluid

Dramatic changes are expected of thermophysical properties near the liquid-gas critical point, which gives rise to the piston effect that accelerates thermal equilibration. On a long timescale, the gravity-induced Rayleigh-Béenard convection, influenced by the piston effect, exhibits features different from normal fluids. By the use of the SIMPLE algorithm, we study the evolution of convection in supercritical nitrogen at different proximities to the critical point. The results show that fluid motion is dominated by turbulent thermal plumes extremely close to the critical point. As the distance to the critical point grows, the formation of the flow pattern resembles that of a weakly compressible fluid.