A hierarchical levitating cluster containing transforming small aggregates of water droplets

A new type of levitating droplet cluster composed of often transforming small aggregates of water droplets is described for the first time. Unlike earlier observed droplet clusters controlled by aerodynamic forces, which formed either an ordered hexagonal structure or a chain structure, the cluster under consideration has a hierarchical organization. Small groups of closely spaced or packed droplets with interactions controlled by the electrostatic force are combined into larger structures controlled by aerodynamic forces. Since charged droplets in the nucleus of the cluster do not have dynamically stable configurations, droplet aggregates keep continuously restructuring. However, droplets with lower charges in external layers of the cluster form a stable hexagonal structure. Graphical abstract: Levitating hierarchical droplet cluster build of small droplet groups. [Figure not available: see fulltext.].