Non-equilibrium flow of van der Waals fluids in nano-channels

Baochao Shan; Long Ju; Wei Su; Zhaoli Guo; Yonghao Zhang

doi:10.1063/5.0148857

Non-equilibrium flow of van der Waals fluids in nano-channels

Baochao Shan, Long Ju, Wei Su, Zhaoli Guo^*, Yonghao Zhang^*

^*Corresponding author for this work

Research output: Contribution to journal › Article › peer-review

7 Scopus citations

Abstract

The Enskog-Vlasov equation provides a consistent description of the microscopic molecular interactions for real fluids based on the kinetic and mean-field theories. The fluid flows in nano-channels are investigated by the Bhatnagar-Gross-Krook (BGK) type Enskog-Vlasov model, which simplifies the complicated Enskog-Vlasov collision operator and enables large-scale engineering design simulations. The density distributions of real fluids are found to exhibit inhomogeneities across the nano-channel, particularly at large densities, as a direct consequence of the inhomogeneous force distributions caused by the real fluid effects including the fluid molecules' volume exclusion and the long-range molecular attraction. In contrast to the Navier-Stokes equation with the slip boundary condition, which fails to describe nano-scale flows due to the coexistence of confinement, non-equilibrium, and real fluid effects, the Enskog-Vlasov-BGK model is found to capture these effects accurately as confirmed by the corresponding molecular dynamics simulations for low and moderate fluid densities.

Original language	English (US)
Article number	052004
Journal	Physics of Fluids
Volume	35
Issue number	5
DOIs	https://doi.org/10.1063/5.0148857
State	Published - May 1 2023

Bibliographical note

Funding Information:
This work was supported by the UK's Engineering and Physical Sciences Research Council under Grant No. EP/R041938/1 and the National Natural Science Foundation of China under Grant Nos. 51836003 and 12002130. Supercomputing time on ARCHER is provided by the “UK Consortium on Mesoscale Engineering Sciences (UKCOMES)” under the UK Engineering and Physical Sciences Research Council Grant No. EP/R029598/1. This work made use of computational support by CoSeC, the Computational Science Centre for Research Communities, through UKCOMES.

Publisher Copyright:
© 2023 Author(s).

ASJC Scopus subject areas

Computational Mechanics
Condensed Matter Physics
Mechanics of Materials
Mechanical Engineering
Fluid Flow and Transfer Processes

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abstract = "The Enskog-Vlasov equation provides a consistent description of the microscopic molecular interactions for real fluids based on the kinetic and mean-field theories. The fluid flows in nano-channels are investigated by the Bhatnagar-Gross-Krook (BGK) type Enskog-Vlasov model, which simplifies the complicated Enskog-Vlasov collision operator and enables large-scale engineering design simulations. The density distributions of real fluids are found to exhibit inhomogeneities across the nano-channel, particularly at large densities, as a direct consequence of the inhomogeneous force distributions caused by the real fluid effects including the fluid molecules' volume exclusion and the long-range molecular attraction. In contrast to the Navier-Stokes equation with the slip boundary condition, which fails to describe nano-scale flows due to the coexistence of confinement, non-equilibrium, and real fluid effects, the Enskog-Vlasov-BGK model is found to capture these effects accurately as confirmed by the corresponding molecular dynamics simulations for low and moderate fluid densities.",

author = "Baochao Shan and Long Ju and Wei Su and Zhaoli Guo and Yonghao Zhang",

note = "Funding Information: This work was supported by the UK's Engineering and Physical Sciences Research Council under Grant No. EP/R041938/1 and the National Natural Science Foundation of China under Grant Nos. 51836003 and 12002130. Supercomputing time on ARCHER is provided by the “UK Consortium on Mesoscale Engineering Sciences (UKCOMES)” under the UK Engineering and Physical Sciences Research Council Grant No. EP/R029598/1. This work made use of computational support by CoSeC, the Computational Science Centre for Research Communities, through UKCOMES. Publisher Copyright: {\textcopyright} 2023 Author(s).",

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N2 - The Enskog-Vlasov equation provides a consistent description of the microscopic molecular interactions for real fluids based on the kinetic and mean-field theories. The fluid flows in nano-channels are investigated by the Bhatnagar-Gross-Krook (BGK) type Enskog-Vlasov model, which simplifies the complicated Enskog-Vlasov collision operator and enables large-scale engineering design simulations. The density distributions of real fluids are found to exhibit inhomogeneities across the nano-channel, particularly at large densities, as a direct consequence of the inhomogeneous force distributions caused by the real fluid effects including the fluid molecules' volume exclusion and the long-range molecular attraction. In contrast to the Navier-Stokes equation with the slip boundary condition, which fails to describe nano-scale flows due to the coexistence of confinement, non-equilibrium, and real fluid effects, the Enskog-Vlasov-BGK model is found to capture these effects accurately as confirmed by the corresponding molecular dynamics simulations for low and moderate fluid densities.

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Non-equilibrium flow of van der Waals fluids in nano-channels

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