3D characterization of the inner flow in an oscillating drop

In this work, measurements of the velocity field inside a vertically shaken drop are presented. The drop-wetting condition is slightly hydrophobic. The drop is sandwiched between two horizontal glass plates in order to allow a good visualization. Digital in-line holography is utilized to access the three-dimensional flow inside the drop. When shaken, the drop experiences several transitions of its dynamics and shape: At low amplitude, its contact line is pinned and when the amplitude overcomes a threshold, it becomes unpinned. At even higher amplitude, the drop shows the faceted shape of a star. The obtained velocity vector maps are related to the transition in dynamics and shape.