Physics of Fluids - Publications

Bubble size prediction in co-flowing streams

Europhysics Letters 94, 64001 (2011)

Authors

	Wim van Hoeve
	Benjamin Dollet
	José Manuel Gordillo Arias de Saavedra
	Michel Versluis
	Leen van Wijngaarden
	Detlef Lohse

BibTeΧ

@article{0295-5075-94-6-64001,
  author={W. van Hoeve and B. Dollet and J. M. Gordillo and M. Versluis and L. van Wijngaarden and D. Lohse},
  title={Bubble size prediction in co-flowing streams},
  journal={EPL (Europhysics Letters)},
  volume={94},
  number={6},
  pages={64001},
  url={http://stacks.iop.org/0295-5075/94/i=6/a=64001},
  year={2011},
  abstract={In this paper, the size of bubbles formed through the breakup of a gaseous jet in a co-axial microfluidic device is derived. The gaseous jet surrounded by a co-flowing liquid stream breaks up into monodisperse microbubbles and the size of the bubbles is determined by the radius of the inner gas jet and the bubble formation frequency. We obtain the radius of the gas jet by solving the Navier-Stokes equations for low-Reynolds-number flows and by conservation of momentum. The prediction of the bubble size is based on the system's control parameters only, i.e. the inner gas flow rate Q i , the outer liquid flow rate Q o , and the tube radius R . For a very low gas-to-liquid flow rate ratio ( Q i / Q o →0) the bubble radius scales as ##IMG## [http://ej.iop.org/images/0295-5075/94/6/64001/epl13558ieqn1.gif] {r_\mathrm{b}/R \propto \sqrt{Q_\mathrm{i}/Q_\mathrm{o}}} , independently of the inner-to-outer viscosity ratio η i /η o and of the type of the velocity profile in the gas, which can be either flat or parabolic, depending on whether high-molecular-weight surfactants cover the gas-liquid interface or not. However, in the case in which the gas velocity profiles are parabolic and the viscosity ratio is sufficiently low, i.e. η i /η o ##IMG## [http://ej.iop.org/icons/Entities/Lt.gif] {Lt} 1, the bubble diameter scales as r b ∝( Q i / Q o ) β , with β smaller than 1/2.}
}