Numerical Modeling of Flow and Deformations Induced in a Droplet Subjected to Alternating Electric Field

Download or read book Numerical Modeling of Flow and Deformations Induced in a Droplet Subjected to Alternating Electric Field written by Nithin S. Panicker and published by . This book was released on 2012 with total page 82 pages. Available in PDF, EPUB and Kindle. Book excerpt: Numerical investigation of the flow in a drop of a dielectric fluid suspended in another immiscible dielectric fluid in the presence of an alternating electric field has been carried out. When an electric field is applied to a drop of a dielectric fluid, the electric field induces stresses at the fluid interface. The normal stresses deform the drop and the tangential stresses produce a circulatory motion inside and outside the drop. Such electrical field induced flow can lead to significant enhancement of heat or mass transfer to from the drop. A stream function-vorticity approach with a finite volume formulation is adopted to numerically determine the unsteady flow field in the continuous and the dispersed phases. The volume of fluid (VOF) method is used to track the phase boundary and to predict the transient drop shape deformations for a range of capillary numbers. A new VOF formulation with Continuum Surface Force model has been derived and implemented to account for both the tangential and the normal electrical stresses present at the phase interface. Results show that the extent of drop deformation increases with capillary number and the strength of the electric field. By tracking Lagrangian fluid particles inside the deforming droplet, it is seen that the changing flow patterns due to drop deformation lead to significant fluid mixing inside the droplet. Earlier studies available in the literature neglect drop deformations and may significantly underestimate the heat/mass transfer enhancement in the presence of an alternating electric field.