Departmental Papers (MEAM)

Document Type

Journal Article

Date of this Version

March 2008

Comments

Reprinted from Physical Review E, Volume 77, Article 036309, March 2008, 6 pages.
Publisher URL: http://dx.doi.org/10.1103/PhysRevE.77.036309

Abstract

The effects of elasticity on filament thinning and breakup are investigated in microchannel cross flow. When a viscous solution is stretched by an external immiscible fluid, a low 100 ppm polymer concentration strongly affects the breakup process, compared to the Newtonian case. Qualitatively, polymeric filaments show much slower evolution, and their morphology features multiple connected drops. Measurements of filament thickness show two main temporal regimes: flow- and capillary-driven. At early times both polymeric and Newtonian fluids are flow-driven, and filament thinning is exponential. At later times, Newtonian filament thinning crosses over to a capillary-driven regime, in which the decay is algebraic. By contrast, the polymeric fluid first crosses over to a second type of flow-driven behavior, in which viscoelastic stresses inside the filament become important and the decay is again exponential. Finally, the polymeric filament becomes capillary-driven at late times with algebraic decay. We show that the exponential flow thinning behavior allows a measurement of the extensional viscosities of both Newtonian and polymeric fluids.

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Date Posted: 29 April 2008

This document has been peer reviewed.