title: Interaction and coalescence of large bubbles rising in a thin gap.
abstract: We present accurate measurements of the relative motion and deformation of two large bubbles released consecutively in a quiescent liquid confined in a thin-gap cell. Although the second injected bubble was smaller, we observed that, in all cases, it accelerated and caught up with the leading bubble. This acceleration is related to the wake of the leading bubble, which also induces significant changes in the width and curvature of the trailing bubble. On the contrary, the velocity of the leading bubble is unaltered during the whole interaction and coalescence process. Shape adaptation of the two bubbles is observed just prior to coalescence. After pinch-off, the liquid film is drained at a constant velocity.
authors.affiliation: Université de Toulouse, INPT, UPS, Institut de Mécanique des Fluides de Toulouse, Allée Camille Soula, F-31400 Toulouse, France.
authors.forename: Sander G
authors.initials: SG
authors.lastname: Huisman
authors.forename: Patricia
authors.initials: P
authors.lastname: Ern
authors.forename: Véronique
authors.initials: V
authors.lastname: Roig