Mf. Elsayed, EFFECT OF NORMAL ELECTRIC-FIELDS ON KELVIN-HELMHOLTZ INSTABILITY FOR POROUS-MEDIA WITH DARCIAN AND FORCHHEIMER FLOWS, Physica. A, 255(1-2), 1998, pp. 1-14
The linear electrohydrodynamic Kelvin-Helmholtz instability of the int
erface between two dielectric fully saturated porous media under the e
ffect of normal electric fields is considered. The lighter fluid is ab
ove the heavier one so that in the absence of both motion and electric
fields, the arrangement is stable and the interface is flat. It is sh
own that when the fluids are moving parallel to each other at differen
t velocities, the interface may become unstable, and the normal electr
ic fields have usually destabilizing effect. The corresponding conditi
ons for marginal stability are derived for Darcian and Forchheimer flo
ws. In both the cases, the velocities, and the electric fields should
exceed some critical values in order for the instability to manifest i
tself. In the case of Darcy's flow, however, an additional condition,
involving the fluids viscosities, their density ratios and the electri
c field values is required. (C) 1998 Published by Elsevier Science B.V
. All rights reserved.