Bubble entrapment during sphere impact onto quiescent liquid surfaces
Type
ArticleKAUST Department
Clean Combustion Research CenterHigh-Speed Fluids Imaging Laboratory
Mechanical Engineering Program
Physical Science and Engineering (PSE) Division
Date
2011-06-20Online Publication Date
2011-06-20Print Publication Date
2011-08Permanent link to this record
http://hdl.handle.net/10754/561802
Metadata
Show full item recordAbstract
We report observations of air bubble entrapment when a solid sphere impacts a quiescent liquid surface. Using high-speed imaging, we show that a small amount of air is entrapped at the bottom tip of the impacting sphere. This phenomenon is examined across a broad range of impact Reynolds numbers, 0.2 a Re = (DU0/Il) a 1.2' 105. Initially, a thin air pocket is formed due to the lubrication pressure in the air layer between the sphere and the liquid surface. As the liquid surface deforms, the liquid contacts the sphere at a finite radius, producing a thin sheet of air which usually contracts to a nearly hemispherical bubble at the bottom tip of the sphere depending on the impact parameters and liquid properties. When a bubble is formed, the final bubble size increases slightly with the sphere diameter, decreases with impact speed but appears independent of liquid viscosity. In contrast, for the largest viscosities tested herein, the entrapped air remains in the form of a sheet, which subsequently deforms upon close approach to the base of the tank. The initial contact diameter is found to conform to scalings based on the gas Reynolds number whilst the initial thickness of the air pocket or adimplea scales with a Stokes' number incorporating the influence of the air viscosity, sphere diameter and impact speed and liquid density. © 2011 Cambridge University Press.Citation
MARSTON, J. O., VAKARELSKI, I. U., & THORODDSEN, S. T. (2011). Bubble entrapment during sphere impact onto quiescent liquid surfaces. Journal of Fluid Mechanics, 680, 660–670. doi:10.1017/jfm.2011.202Sponsors
This work was partially supported by KAUST AEA grant 7000000028.Publisher
Cambridge University Press (CUP)Journal
Journal of Fluid Mechanicsae974a485f413a2113503eed53cd6c53
10.1017/jfm.2011.202