Stretching, droplets & instabilities in non-newtonian flow: The role of visco-elasticity

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• Jerry Gollub, Department of Physics, Haverford College
• Thursday 04 December 2008, 11:30-12:30
• Open Plan Area, BP Institute, Madingley Rise CB3 0EZ.

If you have a question about this talk, please contact Dr C. P. Caulfield.

Viscoelastic fluids (e.g. polymeric solutions) can flow in surprising ways. This talk presents several examples, based on experiments at small scales, in microfluidic channels.

• The stretching of thin filaments, and their breakup into droplets, has a quite different morphology and rate compared to Newtonian fluids of similar viscosity.
• When polymer molecules pass near the hyperbolic point of a microchannel cross flow, they are strongly stretched. As the strain rate is varied at low Reynolds number (< 100), tracer and particle-tracking experiments show that molecular stretching produces two flow instabilities: one in which the velocity field becomes strongly asymmetric, and a second in which it fluctuates non-periodically in time. The flow is strongly perturbed even far from the region of instability and this phenomenon can be used to produce mixing.

(Work done with P.E. Arratia and D. Durian)

This talk is part of the Institute for Energy and Environmental Flows (IEEF) series.

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• Open Plan Area, BP Institute, Madingley Rise CB3 0EZ
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