Critical slowing down and fading away of the piston effect in porous media
OUAZZANI, Jalil
Institut de Chimie de la Matière Condensée de Bordeaux [ICMCB]
ESEME : Équipe du Supercritique pour l'Environnement, les Matériaux et l'Espace : Équipe commune CEA-CNRS (2000-2014)
Institut de Chimie de la Matière Condensée de Bordeaux [ICMCB]
ESEME : Équipe du Supercritique pour l'Environnement, les Matériaux et l'Espace : Équipe commune CEA-CNRS (2000-2014)
GARRABOS, Yves
Institut de Chimie de la Matière Condensée de Bordeaux [ICMCB]
ESEME : Équipe du Supercritique pour l'Environnement, les Matériaux et l'Espace : Équipe commune CEA-CNRS (2000-2014)
< Reduce
Institut de Chimie de la Matière Condensée de Bordeaux [ICMCB]
ESEME : Équipe du Supercritique pour l'Environnement, les Matériaux et l'Espace : Équipe commune CEA-CNRS (2000-2014)
Language
en
Document de travail - Pré-publication
English Abstract
We investigate the critical speeding up of heat equilibration by the piston effect (PE) in a nearly supercritical van der Waals (vdW) fluid confined in a homogeneous porous medium. We perform an asymptotic analysis of the ...Read more >
We investigate the critical speeding up of heat equilibration by the piston effect (PE) in a nearly supercritical van der Waals (vdW) fluid confined in a homogeneous porous medium. We perform an asymptotic analysis of the averaged linearized mass, momentum and energy equations to describe the response of the medium to a boundary heat flux. While nearing the critical point (CP), we find two universal crossovers depending on porosity, intrinsic permeability and viscosity. Closer to the CP than the first crossover, a pressure gradient appears in the bulk due to viscous effects, the PE characteristic time scale stops decreasing and tends to a constant. In infinitly long samples the temperature penetration depth is larger than the diffusion one indicating that the PE in porous media is not a finite size effect as it is in pure fluids. Closer to the CP, a second cross over appears which is characterized by a pressure gradient in the thermal boundary layer (BL). Beyond this second crossover, the PE time remains constant, the expansion of the fluid in the BL drops down and the PE ultimately fades away.Read less <
English Keywords
Critical point
Piston effect
Porous media
Origin
Hal imported