This paper presents investigations on the partial coalescence of an aqueous drop with an organic-aqueous interface with and without surfactants. The organic phase was different silicone oils and the aqueous phase was a glycerol-water solution at different concentrations. It is found that when the surfactant Span 80 is introduced into the organic phase, the partial coalescence region is reduced in the Oh–Bo coalescence map. The range of the inertio-capillary regime reduces when surfactants are present, while the drop size ratio decreases with increasing surfactant concentration. The velocity fields inside the aqueous drop were studied with high speed particle image velocimetry for the first time. In the surfactant-free system, it was found that the inward motion of the fluids at the upper part of the drop favours the generation of a liquid cylinder at the early stages of coalescence. The pressure gradient created by the downward stream at the bottom of the liquid cylinder drives the pinch-off of the second...

中文翻译：

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表面活性剂液滴/界面部分聚结的实验研究

本文介绍了在有和没有表面活性剂的情况下，具有有机-水界面的水滴部分聚结的研究。有机相为不同的硅油，水相为不同浓度的甘油-水溶液。发现当表面活性剂 Span 80 被引入有机相时，Oh-Bo 聚结图中的部分聚结区域减少。当存在表面活性剂时，惯性-毛细管范围减小，而液滴尺寸比随着表面活性剂浓度的增加而减小。首次用高速粒子图像测速仪研究了水滴内部的速度场。在不含表面活性剂的体系中，结果表明，液滴上部流体的向内运动有利于在聚结的早期阶段产生液柱。由液缸底部向下流产生的压力梯度驱动第二...