Document Type

Journal Article

Role

author

Standard Number

0031-9007

Journal Title

Physical Review. Letters

Volume

96

Issue

14

First Page

144502

Publication Date

2006

Abstract

This paper, which has two Haverford student co-authors, shows novel instabilities of polymer solutions at low Reynolds number, under conditions where ordinary fluids would not show any instability. At low Reynolds number, viscoelastic fluids can exhibit instabilities in flows that have curved streamlines. We are exploring the behavior of viscoelastic solutions in a microchannel cross flow that contains a stagnation point. We have developed the capability of studying the velocity field as a function of time by tracking fluorescent particles. From the velocity fields, we can determine the position of the stagnation point accurately. We find that when the shear rate is sufficiently high in comparison to the inverse of the polymer relaxation time, the position of the stagnation point begins to fluctuate. The effect does not occur for rigid polymer solutions, or for Newtonian fluids. -- author-supplied description

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