Impact of drops on the surface of immiscible liquids

Impact of drops on the surface of an immiscible liquid is studied. We show that in addition to the commonly-observed lens structure at the air–liquid interface, drops released from critical heights above the target liquid can sustain the impact and at the end maintain a spherical ball-shape configuration above the surface despite undergoing large deformation. The existence of this metastable state of the drop above the free surface and its transition into the more stable submerged lens configuration at the air–liquid interface is investigated. The initial impact which induces the degree of submergence is critically related to the two distinct life paths of drops impinging upon a liquid surface.

Graphical abstractDrops released on the free surface of an immiscible liquid usually form a partially-submerged lens structure. In addition to this configuration, it is shown that a drop released from a range of critical heights can sustain the impact and at the end maintain a spherical ball-shape above the surface despite undergoing large deformation. This spherical configuration of drops at the air–liquid interface is metastable and transforms into the stable submerged lens-shape in a fraction of a second.Figure optionsDownload full-size imageDownload high-quality image (27 K)Download as PowerPoint slideResearch highlights► Low speed impact of water drops on the surface of fluorocarbon liquid is investigated. ► In addition to the familiar lens configuration, drops released from critical heights can sustain the impact and form a spherical ball-shape structure above the surface. ► Transition of metastable spherical drops into a stable lens configuration at the interface is studied.