New Jersey Institute of Technology
Department of Mathematical Sciences

Capstone Laboratory

The Shape of a Soap Film in an Electric Field

Supported by NSF grant No. 0511514

Instructor: Michael R. Booty

The project combined analysis and computation with modeling and simple experiments to see how an electrostatic field can alter the shape of a soap film or fluid membrane. Some appreciation that objects can experience a force when placed in an electrostatic field was around before 1752 when Benjamin Franklin used the idea in the invention of "Franklin's Bells". Various types of electroscope were invented soon after. A more quantitative understanding of how an electrostatic field can deform continuous media must have waited for formulation of the Maxwell stress tensor. Our project draws on studies by G.I. Taylor during the 1960's on liquid drops coalescing or breaking up in an electric field (cf. drops in a rain cloud) and the "Taylor cone", which is related to experiments by Zeleny (1917) on electrohydrodynamic "jetting". More recently, electrohydrodynamics has become a topic of interest for the control of a fluid, or of drops and bubbles, in small-scale microfluidic devices, and in solid-phase MEMS that have a variety of applications.

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