The air entrapment under a drop impacting on a nano-rough surface
Type
ArticleKAUST Department
Clean Combustion Research CenterHigh-Speed Fluids Imaging Laboratory
Mechanical Engineering Program
Physical Science and Engineering (PSE) Division
KAUST Grant Number
URF/1/2621-01-01Date
2018Permanent link to this record
http://hdl.handle.net/10754/628387
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We study the impact of drops onto a flat surface with a nano-particle-based superhydrophobic coating, focusing on the earliest contact using 200 ns time-resolution. A central air-disc is entrapped when the drop impacts the surface, and when the roughness is appropriately accounted for, the height and radial extent of the air-disc follow the scaling laws established for impacts onto smooth surfaces. The roughness also modifies the first contact of the drop around the central air-disc, producing a thick band of micro-bubbles. The initial bubbles within this band coalesce and grow in size. We also infer the presence of an air-film residing inside the microstructure, at radial distances outside the central air-disc. This is manifest by the sudden appearance of microbubbles within a few microseconds after impact. The central air-disc remains pinned on the roughness, unless it is chemically altered to make it superhydrophilic.Citation
Langley KR, Li EQ, Vakarelski IU, Thoroddsen ST (2018) The air entrapment under a drop impacting on a nano-rough surface. Soft Matter. Available: http://dx.doi.org/10.1039/c8sm01070f.Sponsors
The authors would like to thank Peter Hicks for useful discussions. The work reported herein was supported by funding from King Abdullah University of Science and Technology (KAUST) under Grant No. URF/1/2621-01-01. E. Q. Li acknowledges the Thousand Young Talents Program of China, the National Natural Science Foundation of China (Grant No. 11772327, 11642019, & 11621202) and Fundamental Research Funds for the Central Universities (Grant No. WK2090050041).Publisher
Royal Society of Chemistry (RSC)Journal
Soft MatterAdditional Links
http://pubs.rsc.org/en/content/articlehtml/2018/sm/c8sm01070fae974a485f413a2113503eed53cd6c53
10.1039/c8sm01070f
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Except where otherwise noted, this item's license is described as This Open Access Article is licensed under a Creative Commons Attribution 3.0 Unported Licence