Axisymmetric and non-axisymmetric instability of an electrically charged viscoelastic liquid jet

Abstract

A linear analysis is performed to investigate the competition between axisymmetric and non-axisymmetric instability of an electrically charged viscoelastic liquid jet. The liquid is assumed to be a dilute polymer solution modeled by the Oldroyd-B constitutive equation. As to its electric properties, the liquid is assumed to be of finite electrical conductivity and is described by the Taylor–Melcher leaky dielectric theory. An analytical dispersion relation is derived and the temporal growth rate is solved numerically. Two viscoelastic liquids, i.e. a PEO aqueous solution and a PIB Boger fluid, are taken as examples to study the effects of electric field and electrical conductivity on jet instability. The result shows that electric field basically destabilizes both the axisymmetric and the non-axisymmetric mode. On the other hand, the effect of electrical conductivity on the modes is quite limited. An energy analysis shows that elasticity enhances both axisymmetric and non-axisymmetric jet instability and its destabilization effect on the axisymmetric mode is more profound. For viscoelastic jets of high Deborah numbers the combined effect of viscosity and elasticity is possibly characterized by an equivalent Reynolds number related only to the viscosity of solvent.