2016
Dr. Isabelle Raspo from the University of Marseille
July 20th 2016, 3:30 pm
Simulation of peculiar behaviors of near-critical fluids
In the proximity of the liquid-gas critical point, several thermodynamic properties and transport coefficients of a fluid exhibit divergent or vanishing behaviors. For instance, the isothermal compressibility, the thermal expansion coefficient or the heat capacity at constant pressure diverge whereas the surface tension, the heat diffusivity or the sound velocity tend to zero. These critical behaviors obviously influence the response of the fluid to external disturbances such as a local heating, gravity, vibrations or others [1]. For instance, when a fluid is locally heated, temperature equilibration is achieved very fast by means of a fourth adiabatic heat transfer mechanism, called the piston effect [2-4], while density relaxes very slowly through diffusion in a quasi-isothermal medium. In the case of a mixture, the problem becomes much more complex since some properties of the solute also exhibit a divergent behavior near the solvent's critical point. In this talk, I will present some problems for which the critical behaviors of the thermodynamic properties and transport coefficients modify the results obtained in near-critical fluids compared to "classical" fluids (namely perfect gases or liquids) [5-7]. Simulations are performed using the Navier-Stokes equations coupled with the energy equation, a cubic equation of state and the species diffusion equation in the case of a mixture, in the Low Mach number approximation.
REFERENCES
[1] B. Zappoli, C. R. Mecanique (2003) 331, 713-726.
[2] H. Boukari, J.N. Shaumeyer, M.E. Briggs, R.W. Gammon, Phys. Rev. A (1990) 41, 2260-2263
[3] A. Onuki, H. Hao, R. Ferrell, Phys. Rev. A (1990), 41, 2256-2259.
[4] B. Zappoli, D. Bailly, Y. Garrabos, B. Le Neindre, P. Guenoun, D. Beysens, Phys. Rev. A (1990) 41, 2264-2267.
[5] I. Raspo, S. Meradji, B. Zappoli, Chem. Eng. Sci. (2007), 62, 4182-4192.
[6] D. Ameur, I. Raspo, Comp. Thermal Sci. (2013), 5(2), 107-118.
[7] M. Wannassi, I. Raspo, J. Supercrit. Fluids, accepted.