Binodal layer in isentropically expanding slab target with van der Waals equation of state

TL;DR

This paper investigates the properties of the binodal layer during isentropic expansion of Van der Waals fluid in a finite slab, revealing how phase transition influences the expansion dynamics.

Contribution

It provides a semi-analytical study of the thermodynamic and kinematic parameters of the binodal layer in a finite slab using Van der Waals EOS.

Findings

Identification of the binodal layer characteristics during expansion.

Analysis of the influence of phase transition on expansion parameters.

Extension of previous models to finite slab geometry.

Abstract

Pecularities of isentropic expansion of warm dense matter (WDM) created by intense energy fluxes are under discussion in situation when thermodynamic trajectory of such expansion crosses binodal of liquid-gas phase transition and expansion within two-phase region is going along equilibrium branch of the isentrope for two-phase mixture . It is known for the case of plane geometry (Anisimov, Inogamov et al. 1999) that because of sharp break of the expansion isoentrope at boiling point there appears extended zone (liquid layer) of uniformity for expanding material with constant thermodynamic and kinematic parameters, which corresponds to the state on binodal. General properties of such boiling (binodal) layer were claimed and discussed before for the cases of isentropic expansion of infinite sample as well as for finite plane and spherical samples (slab and ball) and for the system of well positioned slabs (stuck target). Thermodynamic and kinematic parameters of discussed binodal layer are studied in present paper with the use of simplest Van der Waals equation of state (EOS). Advantage of VdW-EOS is possibility of demonstrable and semi-analytical description of thermo- and hydrodynamics of the process. Current work studies phenomenon in planar case of isentropic expansion of finite sized layer (slab) of VdW-matter.