Double Contact During Drop Impact on a Solid Under Reduced Air Pressure
KAUST DepartmentPhysical Sciences and Engineering (PSE) Division
KAUST Grant NumberURF/1/2621-01-01
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AbstractDrops impacting on solid surfaces entrap small bubbles under their centers, owing to the lubrication pressure which builds up in the thin intervening air layer. We use ultrahigh-speed interference imaging, at 5 Mfps, to investigate how this air layer changes when the ambient air pressure is reduced below atmospheric. Both the radius and the thickness of the air disc become smaller with reduced air pressure. Furthermore, we find the radial extent of the air disc bifurcates, when the compressibility parameter exceeds similar to 25. This bifurcation is also imprinted onto some of the impacts, as a double contact. In addition to the central air disc inside the first ring contact, this is immediately followed by a second ring contact, which entraps an outer toroidal strip of air, which contracts into a ring of bubbles. We find this occurs in a regime where Navier slip, due to rarefied gas effects, enhances the rate gas can escape from the path of the droplet.
CitationLi EQ, Langley KR, Tian YS, Hicks PD, Thoroddsen ST (2017) Double Contact During Drop Impact on a Solid Under Reduced Air Pressure. Physical Review Letters 119. Available: http://dx.doi.org/10.1103/PhysRevLett.119.214502.
SponsorsThis study was supported by King Abdullah University of Science and Technology (KAUST) under Grant No. URF/1/2621-01-01. E. Q. L. acknowledges the Thousand Young Talents Program of China, the National Natural Science Foundation of China (Grants No. 11642019, No. 11772327, and No. 11621202) and Fundamental Research Funds for the Central Universities (Grant No. WK2090050041).
PublisherAmerican Physical Society (APS)
JournalPhysical Review Letters