Statics and dynamics in binary mixtures near the liquid-vapor critical line

Abstract

Static and dynamic properties are investigated near the liquid-vapor critical line in fluid binary mixtures. Simple expressions are given for thermodynamic derivatives and transport coefficients in terms of parameters characterizing the coexistence surface in thep-T-Δ space, where Δ is the chemical potential difference. It becomes possible to understand special crossover phenomena occurring when fluids are nearly azeotropic or when the concentration dependence of the critical temperatureT c (X) [or the critical pressurep c (X)] is weak. The results are used to explain recent data on3He-4He mixtures that apparently contradict previous theories. As a by-product, general relations are found for correlation functions of dynamic variables and thermodynamic derivatives in fluid mixtures.