open access

https://hdl.handle.net/2115/87545

Mean-field kinetic theory analysis of vapor flow between evaporating and condensing interfaces in the presence of non-condensable gas molecules

英語

2021-12-22

American Institute of Physics (AIP)

Physics of Fluids

33(12)

122017

To investigate the vapor kinetic boundary condition (which is the boundary condition for the Boltzmann equation) in the presence of a non-condensable (NC) gas at a non-equilibrium liquid interface, we performed numerical simulations of non-equilibrium vapor (condensable gas) and NC gas mixture flows. The Enskog–Vlasov direct simulation Monte Carlo method (EVDSMC method) was utilized for this two-surface problem to obtain the evaporation and condensation coefficients, which represent the vapor–molecule evaporation and condensation rates, respectively. These coefficients are incorporated in the kinetic boundary condition. The simulation results showed that the evaporation and condensation coefficients decrease with increasing numbers of NC-gas molecules at the liquid interface with the same tendency. To investigate the validity of these coefficients, we also utilized the obtained evaporation and condensation coefficients for Boltzmann equation analysis. Hence, we concluded that these coefficients simply depend on the NC-gas number density at the liquid interface if the liquid temperature is constant. Thus, they are independent of the non-equilibrium or equilibrium state, and therefore, the coefficient values obtained for the equilibrium state can be used in the analysis of a non-equilibrium state. This finding will aid future predictions of non-equilibrium vapor flows with NC gas.

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Version of Record

This article may be downloaded for personal use only. Any other use requires prior permission of the author and AIP Publishing. This article appeared in Physics of Fluids 33, 122017 (2021) and may be found at https://doi.org/10.1063/5.0073118.

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