Contraction of an air disk caught between two different liquids.
When a drop impacts a pool of liquid it entraps a thin disk of air under its center. This disk contracts rapidly into a bubble to minimize surface energy. Herein we use ultra-high-speed imaging to measure the contraction speed of this disk when the drop and pool are of different liquids. For miscible liquids the contraction rate is governed by the weaker of the two surface tensions. Some undulations are observed on the edge of the disk for a water drop impacting a pool of water, but not on a pool of lower surface tension. Similar results are observed for a pair of immiscible liquids.
Division of Physical Sciences and Engineering and Clean Combustion Research Center, King Abdullah University of Science and Technology, Thuwal 23955-6900, Saudi Arabia.
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Thoraval
Division of Physical Sciences and Engineering and Clean Combustion Research Center, King Abdullah University of Science and Technology, Thuwal 23955-6900, Saudi Arabia.
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Thoroddsen