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Séminaire de Ko Okumura

Quasi two-dimensional dynamics of drops and bubbles : drag friction, film bursting, and coalescence


Ko Okumura

Dept. of Physics
Ochanomizu University
2-1-1, Otsuka, Bunkyo-ku
Tokyo 112-8610

We talk on the dynamics of bubbles and drops confined in two parallel
plates, i.e., in a Hele-Shaw cell. When an air bubble is inserted at the
bottom of the cell half-filled with viscous oil, it slowly rises in the oil
and reaches at the oil-air interface located at the middle of the cell,
forming a semi-circular bubble even though no surfactants are contained in the liquid. The bubble stays there for a while before the disappearance. In other words, the film encapsulating the bubble gradually thins down [1] and finally bursts.
We show that the first rising dynamics, as well as similar rising and
setting dynamics of a fluid drop in another immiscible fluid, can be
observed as simple scaling laws ; these dynamics also provide simple laws for viscous drag friction in the Hele-Shaw cell [2]. The film bursting dynamicsrelated to the bubble dynamics, accompanying with coalescence of a fluid drop to the bath of the same liquid, is studied to provide an example of film bursting where the circular symmetry is broken [3]. We also discuss a different mode of coalescence leading to a dimensional crossover of the dynamics [4].

 

  • [1] Ayako ERI and KO, Phys. Rev. E 76, 060601(R) (2007).
  • [2] Ayako ERI and KO, Soft Matter, 7, 5648 (2011) ; highlighted as hotarticle and made access-free by the publisher.
  • [3] Ayako ERI and KO, Phys. Rev. E 82, 030601(R) (2010).
  • [4] Maria YOKOTA and KO, Proc. Nat. Acad. Sci. (USA), 108, 6395 (2011) ; featured in In this issue (This week in PNAS), PNAS, 108 (2011) 6337.