Multi-directional bubble generated streaming flows

Tamsin A Spelman (1, 2, 3) , Olivier Stéphan (3) , Philippe Marmottant (3)

1 DAMTP - Department of Applied Mathematics and Theoretical Physics
2 School of Mathematics and Statistics, University of Glasgow
3 LIPhy - Laboratoire Interdisciplinaire de Physique [Saint Martin d’Hères]

In previous work, we have demonstrated the use of single-holed Armoured Microbubbles (AMBs) for micro-fluidic mixing and self-propulsion. AMBs are hollow partial spheres, inside which we capture a bubble. Under ultrasound, the bubble oscillates, generating a streaming flow with velocities of 1-100 mm/s in water. In this paper, inspired by our successful fabrication of a C60 geometry (buckyball), we study AMBs with multiple surface holes. We show more holes generate additional pairs of fast circulations around the AMB. However, as the number of holes increases further, the circulations become small and the in-plane flow is dominated by a source or sink flow. For an AMB with two different sized holes, we demonstrate each hole can be independently activated, potentially useful for multi-directional swimming.

Domaines: Acoustique [physics.class-ph]; Mécanique des fluides [physics.class-ph]

Tamsin A Spelman, Olivier Stéphan, Philippe Marmottant. Multi-directional bubble generated streaming flows. Ultrasonics, 2019, ⟨10.1016/j.ultras.2019.106054⟩. ⟨hal-02613741⟩