Instabilities and decay rates of charged viscous liquid jets

The eigenmodes and characteristic frequencies of surface deformations of real fluids in the geometry of a cylindrical jet, which is homogeneously charged, are calculated using the linearized Navier-Stokes equation with free surface boundary conditions. A stability phase diagram in the wavenumber-fissility plane is given. Two types of instabilities are described, surface tension and Coulomb force induced. The known modes for ideal potential flow are extended to arbitrary viscosity. In addition new types of modes are described (eigenfunctions and decay rates) which represent rotational flow and have no correspondence to Rayleigh's jet instability.