超疏水表面上聚合液滴合并诱导跳跃的数值模拟
Numerical simulation of the coalescence-induced polymeric droplet jumping on superhydrophobic surfaces
AI总结：
本文通过三维直接数值模拟研究超疏水表面上粘弹性液滴合并诱导跳跃，揭示弹性与剪切变稀改变速度标度并促进液滴在更高Ohnesorge数下跳离表面。
摘要：
通过三维直接数值模拟，研究了超疏水表面上两个聚合液滴的自驱动跳跃。两个相同的粘弹性流体液滴在接触角为180度的表面上滑动、相遇并合并。液滴采用Giesekus本构方程建模，同时引入粘弹性和剪切变稀效应。采用Cahn-Hilliard相场方法捕捉液滴界面。模拟捕捉了液滴的自发合并与跳跃。在毛细-惯性区和粘性区研究了弹性和剪切变稀对合并与跳跃的影响。结果表明，在大Ohnesorge数下，液滴的弹性改变了已知的牛顿液滴毛细-惯性速度标度；当弹性引起合并液滴可见的形状振荡时，所得粘弹性液滴在比牛顿液滴更大的Ohnesorge数下从表面跳离。数值结果表明，在两个液滴合并期间及脱离之前，聚合物链被拉伸，界面处产生的弹性应力诱导液体跳离表面。本研究表明，粘弹性——许多生物和工业应用中常见——会影响超疏水和自清洁表面上的液滴行为。
英文摘要：
Self-propelled jumping of two polymeric droplets on superhydrophobic surfaces is investigated by three-dimensional direct numerical simulations. Two identical droplets of a viscoelastic fluid slide, meet and coalesce on a surface with contact angle 180 degrees. The droplets are modelled by the Giesekus constitutive equation, introducing both viscoelasticity and a shear-thinning effects. The Cahn-Hilliard Phase-Field method is used to capture the droplet interface. The simulations capture the spontaneous coalescence and jumping of the droplets. The effect of elasticity and shear-thinning on the coalescence and jumping is investigated at capillary-inertial and viscous regimes. The results reveal that the elasticity of the droplet changes the known capillary-inertial velocity scaling of the Newtonian drops at large Ohnesorge numbers; the resulting viscoelastic droplet jumps from the surface at larger Ohnesorge numbers than a Newtonian drop, when elasticity gives rise to visible shape oscillations of the merged droplet. The numerical results show that polymer chains are stretched during the coalescence and prior to the departure of two drops, and the resulting elastic stresses at the interface induce the jumping of the liquid out of the surface. This study shows that viscoelasticity, typical of many biological and industrial applications, affects the droplet behaviour on superhydrophobic and self-cleaning surfaces.
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
