Formation of beads-on-a-string structures during break-up of viscoelastic filaments
Formation of beads-on-a-string structures during break-up of viscoelastic filaments
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DOI：
10.1038/nphys1682
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发表时间：
2010-08-01
期刊：
影响因子：
19.6
通讯作者：
Basaran, Osman A.
中科院分区：
文献类型：
--
作者：
Bhat, Pradeep P.;Appathurai, Santosh;Basaran, Osman A.
粘弹性细丝的断裂在自然界和技术上都很普遍。如果一根细丝是通过在拇指和食指之间滴一滴唾液而形成的，并被拉伸，那么细丝的形态接近于破裂，对应于几个大小的珠子通过细丝相互连接。虽然人们普遍认为，这种串上珠子(BOAS)结构的形成只发生在粘弹性流体中，但其潜在的物理机制仍然不清楚，也存在争议。通过数值模拟，探讨了导致BOAS结构形成的物理机制。计算表明，仅靠粘弹性并不能在两个大得多的主珠之间产生一个小的卫星珠，但它的形成需要惯性。然而，粘弹性增强了珠子的生长并延迟了夹断，这导致了相对较长寿命的珠子结构。我们还首次从理论上证明，在实验中也可以形成更小的亚卫星珠子。
Break-up of viscoelastic filaments is pervasive in both nature and technology. If a filament is formed by placing a drop of saliva between a thumb and forefinger and is stretched, the filament's morphology close to break-up corresponds to beads of several sizes interconnected by slender threads. Although there is general agreement that formation of such beads-on-a-string (BOAS) structures occurs only for viscoelastic fluids, the underlying physics remains unclear and controversial. The physics leading to the formation of BOAS structures is probed by numerical simulation. Computations reveal that viscoelasticity alone does not give rise to a small, satellite bead between two much larger main beads but that inertia is required for its formation. Viscoelasticity, however, enhances the growth of the bead and delays pinch-off, which leads to a relatively long-lived beaded structure. We also show for the first time theoretically that yet smaller, sub-satellite beads can also form as seen in experiments.