Effect of external electric field on dynamics of levitating water droplets

The self-assembled clusters of regularly positioned small droplets were observed for the first time in 2004 by Alexander Fedorets. The recent results on stabilization of droplet clusters enable the laboratory study of specific parameters of chemical and biochemical reactions in the microdroplets. However, the analysis of the cluster behavior under the action of external factors is also continued. Some new experimental findings concerning behavior of a cluster of water droplets levitating over the locally heated water surface are reported in the present paper. It is shown that an external electric field leads not only to an increase in the rate of a condensational growth of droplets but also to a relatively early coalescence of small droplets with water layer. The latter is partially explained by the attraction force arising due to polarization of droplets closely spaced to the water surface. The effect of electric field on size of droplets before their coalescence with water layer is used to estimate an electrical charge of single droplets at the experimental conditions. It is shown that this electric charge does not change the aerodynamic nature of the main forces responsible for both the self-arranging and levitation of small water droplets. The results obtained are expected to be useful for further theoretical modeling of the phenomenon of levitating droplets clusters.