Molecular gas dynamics analysis on condensation coefficient of vapour during gas-vapour bubble collapse
Molecular gas dynamics analysis on condensation coefficient of vapour during gas-vapour bubble collapse
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DOI：
10.1017/jfm.2018.722
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发表时间：
2018-10-12
影响因子：
3.7
通讯作者：
Kon, Misaki
中科院分区：
文献类型：
--
作者：
Kobayashi, Kazumichi;Nagayama, Takahiro;Kon, Misaki
本研究研究了蒸汽的凝结系数对由可凝性气体（蒸汽）和不凝性气体（NC 气体）组成的气泡破裂的影响。我们基于分子气体动力学分析模拟了气泡内的蒸汽和NC气体流动，通过改变NC气体和蒸汽的初始数密度比、初始气泡半径和冷凝系数值来精确复制相变（即蒸发和冷凝）。结果表明，当冷凝系数大于约0.4时，气泡的运动不受冷凝系数值的影响。我们还讨论了气泡破裂最后阶段NC气体在气泡壁处的漂移及其对冷凝系数的影响。我们得出的结论是，由于气液界面处的NC气体分子浓度很高，因此当气泡破裂时，蒸气分子可以表现为NC气体分子。也就是说，当气泡剧烈破裂时，凝结系数几乎达到零。
This study investigates the influence of the condensation coefficient of vapour on the collapse of a bubble composed of condensable gas (vapour) and non-condensable gas (NC gas). We simulated vapour and NC gas flow inside a bubble based on the molecular gas dynamics analysis in order to replicate the phase change (viz., evaporation and condensation) precisely, by changing the initial number density ratio of the NC gas and vapour, the initial bubble radius and the value of the condensation coefficient. The results show that the motion of the bubble is unaffected by the value of the condensation coefficient when that value is larger than approximately 0.4. We also discuss NC gas drift at the bubble wall during the final stage of the bubble collapse and its influence on the condensation coefficient. We conclude that vapour molecules can behave as NC gas molecules when the bubble collapses, owing to the large concentration of NC gas molecules at the gas-liquid interface. That is, the condensation coefficient reaches almost zero when the bubble collapses violently.