Generalized van der Waals equation of state for in-line use in hydrodynamic codes
Basic physical and mathematical properties of one of the simplest generalizations of the van der Waals equation of state (EOS), where the power exponent n in the attractive term is treated as a free parameter, are investigated. The main focus is on the parameter range around the gas-liquid phase transition, and on the possibility of in-line use of the equilibrium EOS branch (based on the Maxwell construction in the phase coexistence region) in one-dimensional (1D) hydrodynamic simulations. Conditions are elucidated for emergence of such flow structures as a 'rarefaction shock' and a 'binodal shelf' in rarefaction waves by unloading of compressed matter into vacuum. The quality of numerical modeling of such structures is illustrated with the 1D Lagrangian code DEIRA.
generalized van der Waals equation of state, hydrodynamic flows with phase transitions