An exact non-equilibrium extrapolation scheme for pressure and velocity boundary conditions with large gradients in the lattice Boltzmann method

Ju, Long; Shan, Baochao; Zhou, Yang; Guo, Zhaoli

doi:10.1016/j.compfluid.2021.105163

Cited by 11 publications

(3 citation statements)

References 24 publications

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“…To eliminate the mismatch, , inspired by the discussion for the single-component single-phase system (Ju et al. 2021), we propose to reconstruct the unknown DDFs at the boundary via the following exact NEQ (eNEQ) scheme: where the correction term is explicitly expressed as The flux curves using the eNEQ scheme are shown in figure 3( c ), and we can see that the diffusion flux can be increased by increasing up to 0.9. Afterward, the diffusion flux slightly decreases, as seen for the case .…”

Section: Model Validationmentioning

confidence: 99%

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Lattice Boltzmann modelling of isothermal two-component evaporation in porous media

et al. 2023

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A mesoscopic lattice Boltzmann model is implemented for modelling isothermal two-component evaporation in porous media. The model is based on the pseudopotential multiphase model with two components to mimic the phase-change component (e.g. water and its vapour) and the non-condensible component (e.g. dry air), and the cascaded collision operator is used to enhance the numerical performance. The model is first analysed based on Chapman–Enskog expansion and then validated by the theoretical solution of an isothermal diffusive evaporation problem. We then discuss in detail the implementation of wettability based on a geometric function scheme and further validate the model with microfluidic evaporation experiments. We apply the method to simulate the convective evaporation of a dual-porosity medium and investigate the effects of inflow vapour concentration ( ${Y_{vapour,in}}$ ) and contact angle ( $\theta$ ) on the evaporation. Simulation results reproduce the typical transition from the constant evaporation regime (CRP) at large liquid saturation (S) to the receding front period (RFP) at small S, with an intermediate falling rate period in between. The dependence of the average evaporation rates on ${Y_{vapour,in}}$ and $\theta$ during CRP and RFP is investigated. A universal scaling formulation for the evaporation rate during CRP is found with respect to the concentration-related mass transfer number $B_Y$ , contact angle $\theta$ and inflow Reynolds number Re, i.e. $E{R_{CRP}} = {k_3}\ln \left ( {1 + {B_Y}} \right ) {\cdot } \left [ {\ln \left ( {1 + {Re}} \right ) + {k_2}} \right ]\left [ {\cos (\theta ) + {k_1}} \right ]$ , where ${k_1}$ , ${k_2}$ and ${k_3}$ are fitting parameters.

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Section: Model Validationmentioning

confidence: 99%

“…, inspired by the discussion for the single-component single-phase system (Ju et al 2021), we propose to reconstruct the unknown DDFs at the boundary via the following exact NEQ (eNEQ) scheme:…”

Section: Achievement Of Large Dry Air Mass Fractionmentioning

confidence: 99%

Lattice Boltzmann modelling of isothermal two-component evaporation in porous media

et al. 2023

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“…where p = nk B T is the homogeneous fluid pressure [47], and µ is the fluid viscosity determined by the Enskog theory [20] for dense fluids as…”

Section: Solution Of the Kinetic Modelmentioning

confidence: 99%

Non-equilibrium flow of dense inhomogeneous fluids in nano-channels

Shan

et al. 2022

Preprint

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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 present fluid flows in nano-channels are investigated by the Enskog-Vlasov-BGK 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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A pore-scale lattice Boltzmann model for solute transport coupled with heterogeneous surface reactions and mineral dissolution

Ju,

Wang,

Shan

et al. 2024

Chemical Engineering Journal

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An exact non-equilibrium extrapolation scheme for pressure and velocity boundary conditions with large gradients in the lattice Boltzmann method

Cited by 11 publications

References 24 publications

Lattice Boltzmann modelling of isothermal two-component evaporation in porous media

Lattice Boltzmann modelling of isothermal two-component evaporation in porous media

Non-equilibrium flow of dense inhomogeneous fluids in nano-channels

A pore-scale lattice Boltzmann model for solute transport coupled with heterogeneous surface reactions and mineral dissolution

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