Lattice Boltzmann study of droplet evaporation on a heated substrate under a uniform electric field

Abstract

In this paper, a two-dimensional hybrid thermal lattice Boltzmann (LB) method coupled with the leaky dielectric model was firstly presented to study droplet evaporation on a heated substrate under the influence of an electric field. Contact angle hysteresis and Marangoni effects are included. The accuracy of this model is validated by simulation a static droplet evaporation and droplet deformation in the electric field. Then, the validated model is used to explore the effects of the electrical field on droplet evaporation, by varying the electric field strength and direction. The electric field is seen to change the droplet morphology, internal flow, heat transfer and thus evaporation time. The droplet is elongated along the direction of the electric field, and the contact angle is reduced. A pair of vortices is formed inside the droplet, which is consistent with the Marangoni flow direction, while the pair of vortices outside the droplet is oriented in the opposite direction to the internal one. For all droplets, the average heat flux to the evaporating is linearly related to the contact line length density. Additionally, it is discovered that applying a vertical electric field increases the evaporation time of a sessile droplet, while applying a horizontal electric field decreases it. Our research aids in achieving precise regulation of droplet evaporation and gives a better understanding of the influence of electric fields on droplet evaporation.