2022 Fiscal Year Final Research Report
Elucidation of non-equilibrium phase change at gas-liquid interface mechanism for mixture gas and its application to molecular multi-phase fluid dynamics
| Project/Area Number |
20K04277
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Multi-year Fund |
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| Section | 一般 |
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| Review Section |
Basic Section 19010:Fluid engineering-related
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| Research Institution | Hokkaido University |
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Principal Investigator |
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| Co-Investigator(Kenkyū-buntansha) |
藤井 宏之 北海道大学, 工学研究院, 助教 (00632580)
渡部 正夫 北海道大学, 工学研究院, 教授 (30274484)
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| Project Period (FY) |
2020-04-01 – 2023-03-31
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| Keywords | 気体論境界条件 / 蒸発係数 / 凝縮係数 / 分子動力学 / 分子運動論 / Enskog-Vlasov方程式 |
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| Outline of Final Research Achievements |
In this study, the kinetic boundary conditions at liquid surfaces in contact with gas mixtures (condensable gas and non-condensable gas) were determined by using molecular dynamics and mean-field kinetic theory analysis to determine the values of the evaporation and condensation coefficients, especially in the gas-liquid non-equilibrium state.
As a result, it was confirmed that the values of condensation and evaporation coefficients are affected by the number of non-condensable gas molecules regardless of the gas-liquid equilibrium or nonequilibrium state. One reason for this is that the number of non-condensable gas molecules near the gas-liquid interface increases when there is a large amount of non-condensable gas in the gas phase. As a result, vapor molecules evaporating from the liquid are more likely to collide with non-condensable gas molecules, and backscattering is suggested to have the effect of returning to the liquid again.
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| Free Research Field |
流体工学
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| Academic Significance and Societal Importance of the Research Achievements |
本研究は，気液界面における熱・物質輸送について重要な因子となる蒸発・凝縮係数を分子シミュレーションを用いて求めた．特に，これまで未解明であった非平衡状態における混合気体に接した液面上の蒸発・凝縮係数の値を決定し，混相流体の力学にその知見を展開することを目指している．本研究成果より，平衡状態・非平衡状態に関わらず，蒸発係数や凝縮係数の値は液体温度と非凝縮気体分子の数で整理できることが明らかとなった．これは，様々な種類の分子について蒸発係数や凝縮係数の値が必要となった場合，気液平衡系のみを解析することで蒸発係数や凝縮係数を決定できることを示唆しており，応用上重要な知見である．
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