Electrohydrodynamics of Drops and Jets

Abstract

Electrohydrodynamics is known for more than century and a huge amount of experimental work has been already done. Principles of Electrohydrodynamics is widely used in industrial application like mixing and demixing of fluid. But analytical study of Electrohydrodynamics is limited for some simple problem like deformation of small droplet in steady and uniform electric field. Numerical method for multi-phase electrohydrodynamic flow can provide significant insight. Present study in this report is focused Drop Coalescence under the influence of electric field. All cases are studied under steady and uniform electric field. Present formulation is successfully validated on the problems of drop coalescence without electric field and deformation of drop in presence of electric field with published results. Electrically conductive (instant charge accumulation at interface compare to fluid motion time scale) two-fluid system of density ratio (light to heavy) X = 0.92 and viscosity ratio (light to heavy) n = 46.5 at Reynolds number Re = 100 is simulated here. Electric field intensity (defined using electric bond number - BoE ) and fluid conductivity ratio - B (heavy to light) are selected as system variables to assess the effect of external electric field on interface dynamics. Six cases of electro-coalescence are simulated for three different values of B =10, 102 and 103, each at low and moderately high electric field intensity corresponding to BoE = 0.05 and 0.25. Three different phenomenon of coalescence observed during this study: first, Complete Coalescence; second, Partial Coalescence with Hanging Drop; and third, Taylor Cone.