Ultrasound-induced coalescence of free gas microbubbles

Michiel Postema, Philippe Marmottant, Charles T. Lancée, Michel Versluis, Sascha Hilgenfeldt, Nico De Jong

Research output: Contribution to journalConference articlepeer-review


When gas hubbies collide, the following stages of bubble coalescence have been reported: flattening of the opposing bubble surfaces prior to contact, drainage of the interposed liquid film toward a critical minimal thickness, rupture of the liquid film, and formation of a single bubble. During insonification, expanding contrast agent microbubbles may collide with each other, resulting in coalescence or bounce. In this study, we investigate the validity of the film drainage formalism for expanding free bubbles, by subjecting rigid-shelled contrast agent microbubbles to ultrasound, in order to release gas, and photograph the coalescence of these free gas bubbles. As with colliding bubbles, bubble surface flattening is related to the Weber number. Only inertial film drainage between free interfaces explains the observed coalescence times. In accordance with theory, smaller bubble fragments coalesce on very small time scales, while larger bubbles bounce off each other.

Original languageEnglish (US)
Pages (from-to)1-4
Number of pages4
JournalProceedings - IEEE Ultrasonics Symposium
StatePublished - 2004
Externally publishedYes
Event2004 IEEE Ultrasonics Symposium - Montreal, Que., Canada
Duration: Aug 23 2004Aug 27 2004

ASJC Scopus subject areas

  • Acoustics and Ultrasonics


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