Study of the electrohydrodynamics of a droplet during the impact process on a heated surface in the film evaporation regime

In this research, the electrohydrodynamics of a droplet impacting a hydrophilic heated surface in the deposition regime is studied based on the Taylor’s leaky dielectric theory. The available studies in this area are very limited. In this study, for the first time, the droplet impact process on a surface based on a sharp version of the level-set method is simulated and discontinuous quantities at the interface are modeled accurately. The droplet spreading extent on the surface and, consequently, the heat transfer rate decrease with an increase in the electric capillary number. At a Reynolds number of 400 and an electric capillary number of 0.49, the maximum spreading radius of the droplet and heat transfer rate decrease 7.6% and 13%, respectively, compared to the case without an electric field. Increasing the electric field strength reduces the amplitude of droplet oscillations and, the droplet reaches equilibrium in a shorter time. Moreover, the maximum spreading radius and the maximum heat transfer rate occurs earlier. Higher the electric conductivity and permittivity ratios enhance both the droplet spreading extent and the heat transfer rate. At a Reynolds number of 400 and electric capillary number of 0.22, increasing the electric conductivity ratio from 1000 to 10000 leads to a 6.23% increase in the maximum spreading radius and a 10.33% increase in the heat transfer rate. Similarly, increasing the electric permittivity ratio results in increases of 8.64% and 16.67%, respectively.