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.
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This work was supported by the National Science Foundation Engineering Research Center for Structured Organic Particulate Systems (NSF ERC-SOPS)(EEC-0540855) at Rutgers, Purdue, NJIT and UPRM. G.H.M., acknowledges support from the Nanoscale Interdisciplinary Reasearch Thrust on ‘Directed Self-assembly of Suspended Polymer Fibers’ (NSF-DMS0506941.
The authors declare no competing financial interests.
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Bhat, P., Appathurai, S., Harris, M. et al. Formation of beads-on-a-string structures during break-up of viscoelastic filaments. Nature Phys 6, 625–631 (2010). https://doi.org/10.1038/nphys1682
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