Construction of the equation of state of a porous mixture of condensed species

A method of constructing the equation of state of a simple thermodynamically equilibrium mixture is proposed. The method is based on the hypothesis of additivity of the species volumes. The equilibrium state is determined by the conditions of equality of pressures, temperatures, and velocities of the species. The mixture is described by the model of interpenetrating and interacting continua, which takes into account the gas presence in pores. The equations of state of the mixture and all species, including the gaseous species, are presented in a unified manner (in the form of the Mie–Grüneisen equation). Presentation of functions in the form of Taylor series yields relations that allow the parameters of the equation of state of the mixture to be expressed via the corresponding parameters and mass fractions of individual species. Numerical calculations of shock wave loading and isentropic expansion are performed for solid and porous copper, tungsten, tungsten-copper mixture, and tungsten-nickel-copper mixture. It is demonstrated that the resultant equation of state of the mixture ensures a fairly accurate description of multispecies media with shock and expansion waves propagating in these media.