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Computational Research

Field driven micro-flows: Electrohydrodynamics, magneto-hydrodynamics, electro-kinetics, and electrophoresis.

Field Induced Droplet Generation and Emulsification
Osmotic Flow inside CNTs separated by Graphene Membrane

We have developed a facile and non-invasive way to disintegrate a microdroplet into a string of further miniaturized ones under the influence of an external fields such as electric or magnetic field inside a microchannel for a two-phase flow. The deformation and breakup of the droplet was engendered by the Maxwell’s stress originating from the accumulation of induced and free charges at the oil-water interface. While at smaller field intensities, e.g. less than 1 MV/m, the droplet deformed into a plug, at relatively higher field intensities, e.g. ~1.16 MV/m, a pair of droplets having opposite surface charge was formed. The charged droplets showed an interesting periodic bridging and breakup during their translation motion across the channel. For even higher field intensities, e.g. more than 1.2 MV/m, the entire droplet underwent dielectrophoresis towards one of the electrodes before experiencing a strong attractive force from the other electrode to deform into a shape of a Taylor cone. With progress in time, mimicking the electrospraying phenomenon, the cone-tip periodically ejected a string of miniaturized water droplets to form a microemulsion inside the channel. The frequency and size of the droplet ejection could be tuned by varying the applied field intensity. A water droplet of ~214 μm diameter could continuously eject droplets of size ~10 μm or even smaller to form a microemulsion inside the channel. Presently, we are planning to explore computationally various scientifically interesting and technologically important systems such as the field driven flows inside CNT, on graphene surfaces, or nanochannels as well as the electrophoretic locomotion of nanoscale objects. We ae using computational fluid dynamics, molecular dynamic simulations, and various analytical methods to study explore various interesting aspects of these systems.