Dynamics of liquid jets and threads under the action of radial electric fields: Microthread formation and touchdown singularities

Document Type

Article

Publication Date

1-1-2009

Abstract

We study theoretically the axisymmetric nonlinear dynamics of viscous conducting liquid jets or threads under the action of a radial electric field. The field is generated by a potential difference between the jet surface and a concentrically placed electrode of given radius. We develop a long wave nonlinear model that is used to predict the dynamics of the system and, in particular, to address the effect of the radial electric field on jet breakup. Two canonical regimes are identified that depend on the size of the gap between the outer electrode and the unperturbed jet surface. For relatively large gap sizes, long waves are stabilized for sufficiently strong electric fields but remain unstable as in the nonelectrified case for electric field strengths below a critical value. For relatively small gaps, an electric field of any strength enhances the instability of long waves as compared to the nonelectrified case. We carry out numerical simulations based on our nonlinear models to describe the nonlinear evolution and terminal states in these two regimes. We find that jet pinching does not occur irrespective of the parameters. We identify regimes where capillary instability leads to the formation of stable quasistatic microthreads (connected to large main drops) whose radius decreases with the strength of the electric field. The generic ultimate singular event described by our models is the attraction of the jet surface toward the enclosing electrode and its contact with the electrode in finite time. A self-similar closed form solution is found that describes this event with the interface near touchdown having locally a cusp geometry. The theory is compared to the time-dependent simulations with excellent agreement. © 2009 American Institute of Physics.

Identifier

64249116360 (Scopus)

Publication Title

Physics of Fluids

External Full Text Location

https://doi.org/10.1063/1.3097888

ISSN

10706631

Issue

3

Volume

21

Fund Ref

National Science Foundation

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