Bouncing modes and heat transfer of a dielectric droplet in the presence of an external electric field

초록

A numerical investigation of droplet bouncing and heat transfer over a heated surface in the presence of an external electric field has been reported. The coupled set of governing equations including the electrostatic and incompressible Navier-Stokes equations, have been implemented in the finite-volume framework of OpenFOAM®. The coupled level set and volume of fluid (CLSVOF) approach has been used to capture the droplet interface. The influence of the electric field over the droplet dynamics and bouncing modes are systematically studied. Different bouncing modes are observed and they have been mapped with respect to the electric capillary number, CaE and Weber number, We. Two new modes have been identified at CaE=0.1. The Coulombic attraction at the solid-liquid contact line extends the total contact time of the droplet. The local electric field distribution depends on the droplet's local curvature. The stronger distribution of electrostatic pressure near the tip of the droplet induces a stretching behavior. The stretched droplet, extended contact time and enhanced fluid circulation increase the heat transfer. This work provides a deeper understanding of droplet impact, bouncing dynamics and related heat transfer characteristics influenced by an external electric field. © 2022 Elsevier Ltd

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