The vapor condensation onto a thin liquid film, induced by the reflection of a weak shock wave, is studied by molecular dynamics atomistic simulations of a simple Lennard-Jones fluid. Molecular dynamics results provide reference flowfields for two models. The first one adopts a hybrid continuum-kinetic description in which the liquid phase is described by hydrodynamic equations, whereas the vapor is described by the Boltzmann equation. The structureless liquid-vapor interface is replaced by a classical kinetic boundary condition. The second model is based on the diffuse interface full continuum description of the Lennard-Jones fluid liquid, vapor, and interface regions. For both models, the required fluid thermodynamic and transport properties have been prescribed according to those of the Lennard-Jones fluid. Not unexpectedly, the results show that the continuum-kinetic model provides a good description of molecular dynamics results when the vapor is close to ideal conditions, increasingly deviating from reference data when the vapor non-ideality increases. The opposite behavior is found for the diffuse interface model. It is observed that flow conditions exist where both models fail to provide a reasonably accurate description of reference flow properties.
Simulation of shock induced vapor condensation flows in the Lennard-Jones fluid by microscopic and continuum models
Frezzotti, A.;Barbante, P.
2020-01-01
Abstract
The vapor condensation onto a thin liquid film, induced by the reflection of a weak shock wave, is studied by molecular dynamics atomistic simulations of a simple Lennard-Jones fluid. Molecular dynamics results provide reference flowfields for two models. The first one adopts a hybrid continuum-kinetic description in which the liquid phase is described by hydrodynamic equations, whereas the vapor is described by the Boltzmann equation. The structureless liquid-vapor interface is replaced by a classical kinetic boundary condition. The second model is based on the diffuse interface full continuum description of the Lennard-Jones fluid liquid, vapor, and interface regions. For both models, the required fluid thermodynamic and transport properties have been prescribed according to those of the Lennard-Jones fluid. Not unexpectedly, the results show that the continuum-kinetic model provides a good description of molecular dynamics results when the vapor is close to ideal conditions, increasingly deviating from reference data when the vapor non-ideality increases. The opposite behavior is found for the diffuse interface model. It is observed that flow conditions exist where both models fail to provide a reasonably accurate description of reference flow properties.File | Dimensione | Formato | |
---|---|---|---|
FREZA01-20.pdf
Accesso riservato
Descrizione: Editor's Pick
:
Publisher’s version
Dimensione
1.93 MB
Formato
Adobe PDF
|
1.93 MB | Adobe PDF | Visualizza/Apri |
FREZA_OA_01-20.pdf
Open Access dal 10/12/2020
Descrizione: Paper Open Access
:
Post-Print (DRAFT o Author’s Accepted Manuscript-AAM)
Dimensione
1.25 MB
Formato
Adobe PDF
|
1.25 MB | Adobe PDF | Visualizza/Apri |
I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.