Iterated stretching of viscoelastic jets
نویسندگان
چکیده
We examine, with asymptotic analysis and numerical simulation, the iterated stretching dynamics of FENE and Oldroyd-B jets of initial radius r0 , shear viscosity n, Weissenberg number We, retardation number S, and capillary number Ca. The usual Rayleigh instability stretches the local uniaxial extensional flow region near a minimum in jet radius into a primary filament of radius @Ca(12S)/We#r0 between two beads. The strain-rate within the filament remains constant while its radius ~elastic stress! decreases ~increases! exponentially in time with a long elastic relaxation time 3We(r0 /n). Instabilities convected from the bead relieve the tension at the necks during this slow elastic drainage and trigger a filament recoil. Secondary filaments then form at the necks from the resulting stretching. This iterated stretching is predicted to occur successively to generate high-generation filaments of radius rn , (rn /r0)5&(rn21 /r0) 3/2 until finite-extensibility effects set in. © 1999 American Institute of Physics. @S1070-6631~99!01307-0#
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