Role of the Channel Geometry on the Bubble Pinch-Off in Flow-Focusing Devices

Benjamin Dollet (1) , Wim van Hoeve (2) , Jan-Paul Raven (3) , Philippe Marmottant (3) , Michel Versluis (2)

1 IPR - Institut de Physique de Rennes
2 University of Twente
3 LSP - Laboratoire de Spectrométrie Physique

The formation of bubbles by flow focusing of a gas and a liquid in a rectangular channel is shown to depend strongly on the channel aspect ratio. Bubble breakup consists in a slow linear 2D collapse of the gas thread, ending in a fast 3D pinch-off. The 2D collapse is predicted to be stable against perturbations of the gas-liquid interface, whereas the 3D pinch-off is unstable, causing bubble polydispersity. During 3D pinch-off, a scaling wm˜τ1/3 between the neck width wm and the time τ before breakup indicates that breakup is driven by the inertia of both gas and liquid, not by capillarity.

Mots clés: Drops and bubbles; Interfacial instabilities; Drop and bubble formation

Benjamin Dollet, Wim van Hoeve, Jan-Paul Raven, Philippe Marmottant, Michel Versluis. Role of the Channel Geometry on the Bubble Pinch-Off in Flow-Focusing Devices. Physical Review Letters, 2008, 100 (3), pp.34504. ⟨10.1103/PHYSREVLETT.100.034504⟩. ⟨hal-00674374⟩