Collisions and rebounds of active droplets*

Active droplets undergoing gradual micellar dissolution and spontaneous self-propulsion have recently received much interest as prototypical experimental realisations of synthetic micro-swimmers. While the self-propulsion of a single droplet has been widely studied and is known to arise above a critical advection-to-diffusion ratio, interactions and motion in complex environments remain mostly unexplored due to the non-linearity of the transport equation and its coupling with the flow that prevent the use classical superposition methods.\\ Using a novel numerical framework relying on bi-spherical coordinate we solve the nonlinearly coupled hydrodynamics and solute dynamics exactly, enabling to characterise the rebound for various advection-to-diffusion ratios and to unravel the dominant interactions.