Electrokinetic instability of liquid micro- and nanofilms with a mobile charge

  • The instability of ultra-thin films of an electrolyte bordering a dielectric gas in an external tangential electric field is scrutinized. The solid wall is assumed to be either a conducting or charged dielectric surface. The problem has a steady one-dimensional solution. The theoretical results for a plug-like velocity profile are successfully compared with available experimental data. The linearThe instability of ultra-thin films of an electrolyte bordering a dielectric gas in an external tangential electric field is scrutinized. The solid wall is assumed to be either a conducting or charged dielectric surface. The problem has a steady one-dimensional solution. The theoretical results for a plug-like velocity profile are successfully compared with available experimental data. The linear stability of the steady-state flow is investigated analytically and numerically. Asymptotic long-wave expansion has a triple-zero singularity for a dielectric wall and a quadruple-zero singularity for a conducting wall, and four (for a conducting wall) or three (for a charged dielectric wall) different eigenfunctions. For infinitely small wave numbers, these eigenfunctions have a clear physical meaning: perturbations of the film thickness, of the surface charge, of the bulk conductivity, and of the bulk charge. The numerical analysis provides an important result: the appearance of a strong short-wave instability. At increasing Debye numbers, the short-wave instability region becomes isolated and eventually disappears. For infinitely large Weber numbers, the long-wave instability disappears, while the short-wave instability persists. The linear stability analysis is complemented by a nonlinear direct numerical simulation. The perturbations evolve into coherent structures; for a relatively small external electric field, these are large-amplitude surface solitary pulses, while for a sufficiently strong electric field, these are short-wave inner coherent structures, which do not disturb the surface.show moreshow less

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Metadaten
Author:Georgy S. Ganchenko, Manik Mayur, Evgeny A. Demekhin, Sakir Amiroudine
Creating Corporation:American Institute of Physics
Year of Publication:2015
Pagenumber:41
Language:English
GND Keyword:Elektrokinetische Erscheinung; Instabilität; Mikrofilm; Mobilität
Parent Title (English):Physics of Fluids
Volume:27
Issue:6
ISSN:0899-8213
First Page:062002
Document Type:Article (reviewed)
Institutes:Hochschule Offenburg / Bibliografie
Acces Right:Frei zugänglich
Release Date:2019/10/31
Licence (German):License LogoEs gilt das UrhG
URL:https://www.researchgate.net/publication/279155215_Electrokinetic_instability_of_liquid_micro-_and_nanofilms_with_a_mobile_charge
DOI:https://doi.org/10.1063/1.4921779