Equilibration and other dynamic properties of fluids near the liquid-vapor critical point

A review is presented on the advances in understanding equilibration phenomena in compressible pure fluids near the liquid-vapor critical point. The important role of the piston effect is stressed. The equilibration of temperature and density of a fluid sample, kept in a constant volume, are described. Examples are given both above and below the critical point under Earth's gravity (I g) and microgravity conditions. The good agreement between experimental results and simulations demonstrate the present understanding of the process. The convection onset of a compressible pure fluid in a Rayleigh-Benard cell at I g is described. The impact of the piston effect on the transient, which leads to damped oscillations on the way to reaching a steady state convection, is also described. Here again the results of experiments and numerical simulations are compared. (C) 2004 Academie des sciences. Published by Elsevier SAS. All rights reserved.