TY - JOUR
T1 - Double Contact During Drop Impact on a Solid Under Reduced Air Pressure
AU - Li, Er Qiang
AU - Langley, Kenneth R.
AU - Tian, Yuansi
AU - Hicks, Peter D
AU - Thoroddsen, Sigurdur T.
N1 - This study was supported by King Abdullah University of Science and Technology (KAUST) under URF/1/2621-01-01. Li acknowledges the Thousand Young Talents Program of the National Natural Science Foundation of China (Grant 11621202) and Fundamental Research Funds for the Central Universities (Grant WK2090050041).
PY - 2017/11/24
Y1 - 2017/11/24
N2 - Drops 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 ultra-high-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 becomes smaller with reduced air pressure. Furthermore, wefind the radial extent of the air-disc bifurcates, when the compressibility parameter exceeds 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.
AB - Drops 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 ultra-high-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 becomes smaller with reduced air pressure. Furthermore, wefind the radial extent of the air-disc bifurcates, when the compressibility parameter exceeds 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.
U2 - 10.1103/PhysRevLett.119.214502
DO - 10.1103/PhysRevLett.119.214502
M3 - Letter
SN - 0031-9007
VL - 119
JO - Physical Review Letters
JF - Physical Review Letters
IS - 21
M1 - 214502
ER -
