Experiments and modeling of head-on collision of a pair of bubbles driven by buoyancy in quiescent water are presented. The experiments showed that two bubbles after contacting for a few milliseconds may coalesce or bounce back depending on the collision velocity. As theoretical comparisons, the influence of velocity boundary conditions on the liquid film drainage and the characteristics of two film drainage models with the assumptions of “partially” and fully mobile interfaces under variable-velocity approach condition are studied. The “partially” mobile model is found to be easier to predict rebound case and longer drainage time, and could not obtain the drainage process where the film is thinned to the thickness below 10⁻⁷ m at both low and relatively high Re. As a whole, the fully mobile model with variable-velocity approach shows more reasonable prediction results for the coalescence and rebound of bubbles in the ultrapure water.

中文翻译：

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气泡正面冲撞的实验与建模

介绍了静态水中浮力驱动的一对气泡正面碰撞的实验和建模。实验表明，两个气泡接触几毫秒后，可能会根据碰撞速度而聚结或反弹。作为理论比较，研究了速度边界条件对液膜排水的影响以及在可变速度接近条件下假设“部分”和全流动界面的两个膜排水模型的特性。发现“部分”移动模型更容易预测回弹情况和更长的排水时间，并且在低和相对高的Re下都无法获得将薄膜减薄至10 ^-7 m以下厚度的排水过程。。总体而言，具有可变速度方法的完全移动模型对超纯水中气泡的聚结和回弹给出了更合理的预测结果。