Spatial Instability of Electrically Driven Jets with Finite Conductivity and Under Constant or Variable Applied Field

We investigate the problem of spatial instability of electrically driven viscous jets with finite electrical conductivity and in the presence of either a constant or a variable applied electric field. A mathematical model, which is developed and used for the spatially growing disturbances in electrically driven jet flows, leads to a lengthy equation for the unknown growth rate and frequency of the disturbances. This equation is solved numerically using Newton’s method. For neutral temporal stability boundary, we find, in particular, two new spatial modes of instability under certain conditions. One of these modes is enhanced by the strength  of the applied field, while the other mode decays with increasing . The growth rates of both modes increase mostly with decreasing the axial wavelength of the disturbances. For the case of variable applied field, we found the growth rates of the spatial instability modes to be higher than the corresponding ones for constant applied field, provided  is not too small.