THE CONSTRUCTION OF WIDE-RANGE EQUATIONS OF STATE BY "SEWING" LOCAL EQUATIONS TOGETHER USING MIXTURE MODEL

L.F. Gudarenko, V.G. Kudelkin
VANT. Ser.: Mat. Mod. Fiz. Proc 2000. Вып.4. С. 35-44.

There are some well-known effective semiempirical and theoretical models, which allow constructing sufficiently precise equations of state (EOS). But no model has been constructed to date to create global EOS for computing thermodynamic functions (TDF) of substances within a wide range of density and temperature modification. A proposed means for constructing global EOS consists in "sewing" local EOS together using one of the mixture models. The possibilities of this means are exemplified by constructing the wide-range EOS for iron. The EOS chosen for sewing are the following: a semiempirical EOS which allows computing the area well studied in experiments using shock waves and EOS approximating the computations by a theoretical model of Thomas-Fermi and describing the area of super high pressures and specific energies. A detail description is given of the model, using for sewing local EOS and for computing TDF in a transient area. Diagrams are presented to illustrate the behavior of thermodynamic functions, computed both with wide-range EOS and with local EOS being sewn.
    The authors state their belief that the technique proposed for constructing wide-range EOS has the following advantage: it does not require any modifications of the EOS sewn. Local EOS are only supplemented with the algorithm and program for computing TDF in a transient domain. The example under consideration only uses 14 adjusting parameters, which comply with the requirement for minimum thermodynamic inconsistency and minimum TDF curvature in a transient domain.