Hard-like equation of state

• Published in: Journal of the Physical Society of Japan 2003, Vol.72 (7), p.1689-1697
• Main Authors: KESHAVARZI, Ezat, ROSTAMI, Abbas Ali, TABARINIA, Farzane
• Format: Article
• Language: English
• Subjects: Condensed matter: structure, mechanical and thermal properties; Equations of state, phase equilibria, and phase transitions; Exact sciences and technology; General theory of equations of state and phase equilibria; Physics
• ISSN: 0031-9015; 1347-4073
• DOI: 10.1143/jpsj.72.1689

In a recent article, we have presented a hard-like equation of state, HLEOS, based on the hard-like behavior of fluids at high densities. It has been shown that the hard-like behavior of any real fluid starts at the common bulk modulus point for each isotherm. To confirm our claim, we have shown that the structure factor of real fluids for such conditions may be predicted just using the Percus-Yevick equation for hard fluids. We have introduced and presented an analytical expression for effective pair correlation function at contact, geff(σ), for real fluids that it shows a new corresponding states. The HLEOS predicts thermodynamic properties of all kind of fluids, including non-polar, polar, and hydrogen-bonded systems such as Ar, Xe, CH4, DMB, N2, C2H4, CO, C2H5OH, and H2O successfully. The hard-like EOS has two temperature-dependent parameters, which are related to the soft and hardness of the repulsive branch of the potential. This EOS is also able to predict some known regularities for fluids such as the common bulk modulus point, and common compression point. We have used the HLEOS in prediction of the sound velocity and density for fluids and compared it with the other equations of state.