Spray finishing and inkjet-based electronic devices make are amongst the commercial applications where liquid beads are used to a surface area. However small air bubbles that get caught underneath the bead as it lands can impact the finishing’s quality and harmony.
Sigurdur Thoroddsen and his group from KAUST established an experiment to check whether bubble development would be reduced at lower atmospheric pressure. The group developed a vacuum chamber geared up with a high-speed electronic camera to observe bead bubble development. “Minimizing the atmospheric pressure had numerous benefits, consisting of reducing the bubble size and reducing splashing,” states Kenneth Langley, Thoroddsen’s Ph.D. trainee. However there’s a sweet area, he includes. “We found that if you minimize the pressure excessive, you will entrain more gas bubbles than at greater pressures.”
At these low pressures, the group observed the typical main disk of air is caught, however the bead then suddenly caught a 2nd, external ring of air, which rapidly collapsed into private bubbles (high-speed electronic camera images caught 0.1 split seconds, 1.3 split seconds and 18 split seconds after very first contact of the liquid bead on the glass platform).
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Er Qiang Li et al. Double Contact Throughout Drop Influence On a Strong Under Decreased Atmospheric Pressure, Physical Evaluation Letters(2017). DOI: 10.1103/ PhysRevLett.119214502