Regensburg 2004 – wissenschaftliches Programm
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DY: Dynamik und Statistische Physik
DY 15: Fluids I
DY 15.3: Vortrag
Montag, 8. März 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. Swinney1 — 1University 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