发表机构
Concordia University; McMaster University; M Corporate Research Analytical Laboratory, Polymer Science Group（康科迪亚大学; 麦克马斯特大学; 3M公司企业研究分析实验室，高分子科学组）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本研究实验探究了牛顿与粘弹性空心液滴的冲击动力学，发现粘弹性延迟气泡破裂、抑制脱离并产生串珠结构，且惯性、粘度、毛细力和弹性共同决定沉积、部分沉积或脱离等飞溅形态。
AI 中文摘要
空心液滴的冲击动力学虽然在喷涂和涂覆等应用中具有重要影响，但相较于实心液滴，其研究仍较为匮乏。特别是粘弹性空心液滴的冲击动力学尚未得到充分探索。本研究通过实验探究了空心牛顿（水）液滴和粘弹性（聚合物溶液）液滴在不同冲击速度和聚合物浓度下对固体表面的冲击行为。我们展示了空心液滴铺展的两个标志性特征：中心反向射流的形成和最终沉积，两者均与捕获的气泡相关。对于牛顿液滴，反向射流因毛细不稳定性而表现出快速生长和破裂。引入聚合物添加剂从根本上改变了这一行为：粘弹性影响反向射流的高度和速度，延迟气泡破裂，并抑制液滴脱离。关键在于，我们观察到在细丝拉伸过程中出现了串珠状结构，这是弹性力与毛细力竞争的特征标志。通过系统改变聚合物浓度和冲击速度，我们确定了三种不同结果发生的条件：沉积、部分沉积和脱离。我们的结果表明，惯性、粘度、毛细力和弹性共同控制了空心非牛顿液滴的飞溅形态。
英文摘要
The impact dynamics of hollow droplets, while influential in applications such as coating and spraying, remain less explored than their dense counterparts. In particular, the impact dynamics of viscoelastic hollow droplets have yet to be fully explored. This study presents an experimental investigation into the impact of hollow Newtonian (water) and viscoelastic (polymeric solution) droplets on a solid surface at different impact velocities and polymer concentrations. We demonstrate two hallmark features of hollow droplet flattening: the formation of a central counter-jet and the final deposition, both associated with the entrapped air bubble. For Newtonian droplets, the counter-jet exhibits rapid growth and breakup due to capillary instabilities. Introducing polymer additives fundamentally alters this behavior: viscoelasticity affects the counter-jet's height and velocity, delays bubble rupture, and inhibits droplet detachment. Crucially, we observe the emergence of beads-on-a-string structures during filament thinning, a signature of the competition between elastic and capillary forces. By systematically varying the polymer concentration and impact velocity, we identify the conditions under which three distinct outcomes occur: deposition, partial deposition, and detachment. Our results show how inertia, viscosity, capillarity, and elasticity together govern the splashing morphology of hollow non-Newtonian droplets.
CommentsSubmitted to Physics of Fluids
