Phoretic self-propulsion of microbubbles may contribute to surface cleaning

Abstract

Self-propulsion of small bubbles and droplets through the action of surface-tension gradients is relevant to important processes in both nature and technology, ranging from Marangoni propulsion of microorganisms to transport in microfluidic devices. Here, we use high-fidelity simulations to characterize the fluid dynamical and interfacial phenomena underlying the spontaneous self-propulsion of a small bubble approaching a solid surface. The spreading of surface active contamination at the front of the bubble creates the surface-tension gradient which propels the bubble forward through the Marangoni effect. Results for finite Reynolds numbers and a deformable bubble show that the impact of the active bubble with the solid surface generates fluid stresses that may contribute to the cleaning of fouled surfaces. This effect, however, depends strongly on the initial separation between the bubble and the solid surface.