Seminars

Abstract:
When Lord Rayleigh and other greats of 19 th century physical science were laying down the foundations of fluid dynamics of drops and jets, they could not have imagined that drops and jets would still be of great interest to scientists and engineers in the 21 st century. Indeed, there is currently an explosion of interest in drops and jets because they are scientifically fascinating and technologically important. Whether a millimeter-sized drop drips from the kitchen tap once per second or a stream of micron-sized drops are ejected from the nozzle of an ink jet printer or a DNA/protein arrayer at a rate of 10,000 drops/second, drop formation is a complex free boundary problem exhibiting pinch-off of a fluid interface. Physicists, mathematicians and engineering scientists are drawn to the study of drop breakup because of formation of finite time singularities and self-similar behavior near pinch-off. Computational scientists and engineers are attracted to the problem because it entails large changes in interface topology and the creation of several disconnected liquid masses from an initially single connected liquid mass. Visualization of drop breakup is equally challenging given the micrometer and microsecond length and time scales of interest near pinch-off. This talk will describe recent computational and experimental work aimed at elucidating several interesting situations involving drops and jets. First, the talk will describe analysis of interface rupture using computational algorithms of unprecedented accuracy that accord with scaling theories and ultra high-speed visualization experiments at frame rates up to 100 million pictures per second. Second, the talk will describe how fundamental understanding based on computation and experiment can be used to develop new ways of producing microscopic drops. Two examples to be highlighted include the formation of ultra-small drops from ink jet nozzles and purely hydrodynamic tip streaming induced by flow focusing. The talk will conclude with a glimpse at ongoing work, where some of the aforementioned tools for analyzing drop breakup are being applied to understand how small-scale features and patterns may be formed by electrically-driven instabilities.

For more information, contact Yarin at ayarin@uic.edu

• Spring 2008 Seminar Series