Thermodynamics of a real fluid near the critical point in numerical simulations of isotropic turbulence

• Published in: Physics of fluids (1994) 2016-12, Vol.28 (12)
• Main Authors: Albernaz, Daniel L., Do-Quang, Minh, Hermanson, James C., Amberg, Gustav
• Format: Article
• Language: English
• Subjects: Compressibility; Computational fluid dynamics; Computer simulation; Covariance; Critical point; Energy equation; Equation of state; Equations of state; Fluid dynamics; Fluid flow; Hybrid lattice; Ideal gas; Isotropic turbulence; Kinetic energy; Kinetics; Linearity; Numerical models; Physics; Probability density function; Probability density functions; Real fluids; Reynolds number; Spectral behaviors; Temperature increase; Thermodynamic properties; Thermodynamic variables; Thermodynamics; Turbulence; Turbulent flow; Variation
• ISSN: 1070-6631; 1089-7666; 1089-7666
• DOI: 10.1063/1.4972276

We investigate the behavior of a fluid near the critical point by using numerical simulations of weakly compressible three-dimensional isotropic turbulence. Much has been done for a turbulent flow with an ideal gas. The primary focus of this work is to analyze fluctuations of thermodynamic variables (pressure, density, and temperature) when a non-ideal Equation Of State (EOS) is considered. In order to do so, a hybrid lattice Boltzmann scheme is applied to solve the momentum and energy equations. Previously unreported phenomena are revealed as the temperature approaches the critical point. Fluctuations in pressure, density, and temperature increase, followed by changes in their respective probability density functions. Due to the non-linearity of the EOS, it is seen that variances of density and temperature and their respective covariance are equally important close to the critical point. Unlike the ideal EOS case, significant differences in the thermodynamic properties are also observed when the Reynolds number is increased. We also address issues related to the spectral behavior and scaling of density, pressure, temperature, and kinetic energy.