Influence of confinement on thermodiffusion
Résumé
This work focuses on a possible influence of a nanoporous medium on the thermodiffusion of a fluid "isotopic" mixture. To do so, we performed molecular dynamics simulations of confined Lennard- Jones binary equimolar mixtures using grand-canonical like and non-equilibrium approaches in suband super-critical conditions. The study was conducted in atomistic slit pore of three adsorbent natures for various widths (from 5 to 35 times the size of a molecule). The simulation results indicate that for all thermodynamic conditions and whatever the pore characteristics, the confinement has a negligible effect on the thermal diffusion factor/Soret coefficient. However, when considered separately, the mass diffusion and thermodiffusion coefficients have been found to be largely influenced by the pore characteristics. These two coefficients decrease noticeably when adsorption is stronger and pore width smaller, a behavior that is consistent with a simple hydrodynamic explanation.
Mots clés
Equimolar mixtures
Molecular dynamics simulations
Non equilibrium
Pore characteristics
Thermal diffusion factors
Thermodiffusion
Thermodiffusion coefficients
Thermodynamic conditions Engineering controlled terms: Binary mixtures
Molecular dynamics Engineering main heading: Thermal diffusion in liquids