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Regensburg 2004 – scientific programme

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DY: Dynamik und Statistische Physik

DY 15: Fluids I

DY 15.3: Talk

Monday, March 8, 2004, 15:00–15:15, H3

Holes and fingers in vertically vibrated aqueous suspensions.* — •Florian S. Merkt1,2, Robert D. Deegan1, Daniel I. Goldman1, Erin C. Rericha1, and Harry L. Swinney11University of Texas at Austin — 2presently at the Fritz-Haber-Institut der MPG

We have observed stable holes in a sinusoidally oscillated 0.5 cm deep aqueous suspension of cornstarch for accelerations a above 10g and frequencies of 50-200 Hz. Holes appear only if a finite perturbation is applied to the layer. They are circular and approximately 0.5 cm wide and can persist for more than 105 oscillation periods. Above a≈17g the rim of the hole becomes unstable producing finger-like protrusions or hole division. At even higher accelerations, the hole delocalizes and grows to cover the entire surface with erratic undulations. We have found similar behavior in an aqueous suspension of glass microspheres and argue that shear thickening fluids in general exhibit these patterns.

*Supported by DOE Grant DE-FG03-93ER14312

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