Investigation of the Flow Characteristics of Droplets in Non-uniform Electric field

Abstract

The motion behavior of droplets under non-uniform electric field is an important branch the study of electro-hydrodynamic. In this paper, the theoretical analysis of the force of droplets in non-uniform electric field are carried out, and the study found that the deformation, surface charge density, velocity and other flow characteristics of droplets will change in the effect of non-uniform electric field. In order to study those flow characteristics and the influence of electric field intensity on the deformation and displacement degree of droplets, we will establish the simulation model of droplets and the non-uniform electric field.The results show that the polarization charge distribution on the surface of droplets is not uniform, and the charge density at the center of the electric field is increased gradually; the increase of the electric field intensity in a certain range can increase the droplet shape variable and the moving velocity of the droplet to the concentrated area of the electric field. Introduction The electric field is the fundamental driving force for the liquid drop deformation. Under the non-uniform electric field, the droplets is deformed along the direction of the electric field line and the displacement occurs at the same time to the field intensity concentration.The relevant scholars have carried out the research on the movement behavior of the droplets under the uniform electric field .For example,the dynamics of deformation and rupture of a droplet in uniform electric field is studied by Kazimierzetc. However, previous studies did not involve the movement behavior of liquid droplet deformation and displacement under the action of non-uniform electric field. Therefore, in this paper, based on the level set method of two-phase flow field in Multiphysics COMSOL 4.4, simulation model is established to study the distribution of the potential, electric field, droplets and the velocity vectors around the fluid and the deformation and displacement behaviors of droplets. Model Assumptions To simplify the problem, we make the following assumptions :  The molecular shape of droplet is spherica.  Fluid is an incompressible ideal fluid.  Assuming that there are other fluids around the droplet, the droplet is subjected to the viscous effect of the surrounding fluid. Theoretical analysis in non-uniform electric field Force of droplets in a non-uniform electric field The droplet molecule can be regarded as an electric dipole, the electric dipole moment: ql pe  (1) Where l represents the distance between the point charge. As is shown in Figure 1 below, the electric field force is less than 0 in the non-uniform electric field: 3rd International Conference on Materials Engineering, Manufacturing Technology and Control (ICMEMTC 2016) © 2016. The authors Published by Atlantis Press 996