Electrohydrodynamic instability of two superposed viscous streaming fluids through porous media
1997; NRC Research Press; Volume: 75; Issue: 7 Linguagem: Inglês
10.1139/p97-008
ISSN1208-6045
Autores Tópico(s)Fluid Dynamics and Thin Films
ResumoThe electrohydrodynamic instability of the plane interface between two uniform, superposed viscous streaming dielectric fluids through porous media is considered in the presence of a horizontal electric field. In the absence of surface tension, perturbations transverse to the direction of streaming are found to be unaffected by either the presence of streaming or an electric field as long as perturbations in the direction of streaming are ignored. Whereas for perturbations in all other directions there exists instability for a certain wave-number range. The instability of this system can be delayed by the presence of a tangential electric field. Both the electric field and surface tension are able to suppress Kelvin-Helmholtz instability for small wavelength perturbations and the medium porosity reduces the stability range given in terms of a difference between the streaming velocities and the electric-field effect. For the case in which the heavier fluid overlies the lighter one, it is found that both surface tension and the tangential electric field succeed in stabilizing a certain wave-number range that was unstable in their absence. R´ esum´ e :N ousetudions l'instabilite electrohydrodynamique de l'interface planaire entre deux films dielectriques uniformes et superposes se deplacant a travers un milieu poreux. En l'absence de tension de surface, les perturbations transverses a la direction de circulation du fluide sont insensibles au deplacement ou a la presence d'un champ electrique si nous ignorons les perturbations dans la direction du deplacement. Par contre, avec des perturbations dans toutes les autres directions, il y a possibilite d'instabilite dans un certain domaine du vecteur d'onde. L'instabilite du systeme est reduite par la presence d'un champ electrique tangentiel. Le champ electrique et la tension de surface sont tous deux capables de supprimer l'instabilite de Kelvin-Helmholtz pour des perturbations de petit vecteur d'onde. La porosite du milieu reduit le domaine de stabilite decrit en terme d'une difference entre la vitesse de deplacement et l'effet du champ electrique. Dans le cas ou le fluide lourd est au dessus du fluide leger, la tension de surface et le champ electrique tangentiel reussissent a stabiliser un certain domaine du vecteur d'onde qui etait instable en leur absence. (Traduit par la r ´
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