Antibubble formation by a single drop impact on a free surface

An experimental study of the antibubble formation by a single drop impact on an identical liquid bath is presented. With the increase in the impact velocity, different phenomena are observed and classified into four regimes: No droplet, Single droplet, Double droplets, and Antibubble formation. In fact, the Antibubble formation is part of the Double droplets regime. A high-speed drop impact leads to the formation of a thick jet, which subsequently pinches into two main droplets named as the primary droplet and the secondary droplet. The secondary droplet first impacts on the liquid surface, while the primary droplet then falls back and pushes it into the liquid bath, generating an antibubble. The detailed dynamics is presented, and the critical conditions for antibubble formation are introduced. This work should benefit the controllable generation of antibubbles and stimulate the future applications in practice.