Nonlinear instability of a liquid jet in the presence of a uniform electric field

The nonlinear electrohydrodynamic stability of an irrotational jet in the p resence of capillary force and weak viscous stress on the surface has been studied. Two nonlinear modified Schrodinger equations are obtained. Neglect ing the viscous stress, the classic Schrodinger equations are obtained. The stability conditions of steady state solutions are investigated, using the modulation concept. It is found that the viscous stress produces a resonan ce (say a viscous resonance) away from the critical point. For the progress ive waves, we obtained modified transition curves inserting the viscous str ess. The classic nonlinear cutoff wave number is obtained and this means th at the viscous stress has a fluctuating effect on the perturbed jet, away f rom the critical points. (C) 2000 The Japan Society of Fluid Mechanics and Elsevier Science B.V. All rights reserved.