Seminars & Events

Computations In Science Seminar
"Singularities in Fluid Flow: Pinch-off and Coalescence"

DATE: October 24, 2007
TIME: 12:30 p.m.
SPEAKER: Justin Burton
LOCATION: KPTC 206, University of Chicago

Description:
Our laboratory has worked on pinch-off and coalescence in several unusual experimental fluid systems, including super fluid helium-4. The singularities produced during these events can usually be described by a self-similar form, where quantities such as pressure and velocity diverge and length scales shrink to zero with characteristic power-law exponents. These solutions are often universal in the sense that they do not depend on the initial conditions, but this is not always the case. In most of our experiments, conventional high-speed video is used to examine the pinch-off and coalescence of classical and super fluid liquid drops and gaseous bubbles. However, investigating the asymptotic regime can be difficult due to the finite resolution of the camera and the diffraction of light. To avoid this problem, we developed an electrical technique using drops of liquid mercury to monitor the diameter of the singular region to just a few nanometers. In addition, we have explored the effects of dimensionality on pinch- off and coalescence using thin, quasi-2D liquid lenses floating on water (like drops of oil in vegetable soup). These results have motivated us to investigate idealized 2D pinch-off using boundary- integral simulations. Our analysis shows that unlike axisymmetric drops, non-viscous 2D pinch-off is described by a self-similar solution of the second-kind, where the power-law exponent is a non-rational number. We calculate this number independently solving a nonlinear eigenvalue problem. Another type of singularity in classical fluid flow is the motion of a liquid/solid/gas contact-line (e.g. droplet sliding on a plate). We are currently exploring this problem using super fluid droplets on cesium surfaces. Results and future work will be discussed.

More Information:
Discussion over bag-lunch at 12:15 p.m.
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