A numerical study of viscosity ratio on instability of electrically driven jets

A one-dimensional Giesekus constitutive equation for a straight electrically driven jet is integrated into the governing equations. Axisymmetric stability of the electrically driven jet is analyzed using small perturbation method. In the model, the solvent is treated as Newtonian fluid and the polymer as a viscoelastic fluid, with viscosity ratio of polymer to solvent being treated as an important parameter. Our results show that polymer to solvent viscosity ratio affects stability of the straight electrically driven jet. Small viscosity does not necessarily induce instability and it is only when the viscosity is small and the polymer to solvent viscosity ratio is large that instability occurs. The viscosity ratio is closely related to the elasticity of Giesekus fluid with the fact that large elasticity destabilizes the straight electrically driven jet.