Science / Technology - Colloquium
Monday, February 5, 2007
4:00 PM-5:00 PM
Olin Hall
107
The simplest models of matter posit a linear relationship between the stress
and deformation, as for example in Hooke's law. However, many useful and
important fluids (such as, shampoos, industrial slurries, geophysical fluids, polymeric melts) exhibit a nonlinear response to stress. I will discuss the behaviour of shear thickening fluids subjected to vertical vibrations in the context of pattern forming systems. I will show that a mixture of cornflour/water or glass beads/water vibrated above a critical acceleration (approximately 10 g) is unstable to perturbations. At low accelerations a small indentation of the fluid surface will grow until it reaches the bottom of the container, forming a circular hole. At higher accelerations the rim of the hole becomes unstable and develops an upward
growing tongue. At even higher accelerations, the entire layer writhes in
a disordered manner. The mechanism for these instabilities is unknown. I will present experimental correlations between these instabilities and the fluid's rheological proprieties.
Cost: FREE
Suggested Audiences: College
E-mail:
snj@wpi.edu
Phone: 508-831-5392
Last Modified: February 2, 2007 at 8:35 AM
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