Hydrodynamic instabilities in annular flows subjected to orthogonal unipolar injection

The linear instability of annular Poiseuille flow subjected to an orthogonal unipolar injection with an imposed radial electric field is examined. For low values of Reynolds number the mode of instability is purely electrodynamical. In this region the only effect of the forced flow is the suppression of transverse wavenumber components for the disturbances. In the high Reynolds number region the inertial mode of instability dominates the perturbation dynamics, the electric mechanism being added almost algebraically, thus lowering the critical Reynolds number