Journal of Fluid Mechanics

Papers

Dynamics of bead formation, filament thinning and breakup in weakly viscoelastic jets

A. M. ARDEKANIa1 c1, V. SHARMAa1 and G. H. McKINLEYa1

a1 Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA

Abstract

The spatiotemporal evolution of a viscoelastic jet depends on the relative magnitude of capillary, viscous, inertial and elastic stresses. The interplay of capillary and elastic stresses leads to the formation of very thin and stable filaments between drops, or to ‘beads-on-a-string’ structure. In this paper, we show that by understanding the physical processes that control different stages of the jet evolution it is possible to extract transient extensional viscosity information even for very low viscosity and weakly elastic liquids, which is a particular challenge in using traditional rheometers. The parameter space at which a forced jet can be used as an extensional rheometer is numerically investigated by using a one-dimensional nonlinear free-surface theory for Oldroyd-B and Giesekus fluids. The results show that even when the ratio of viscous to inertio-capillary time scales (or Ohnesorge number) is as low as Oh ~ 0.02, the temporal evolution of the jet can be used to obtain elongational properties of the liquid.

(Received June 10 2010)

(Revised September 10 2010)

(Accepted September 10 2010)

Key words:

  • jets;
  • rheology;
  • viscoelasticity

Correspondence:

c1 Email address for correspondence: ardekani@mit.edu

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