Seminar über aktuelle Fragen zur Dynamik komplexer Fluide: Physicochemical hydrodynamics of confined pumping droplets

Oil droplets in aqueous surfactant solution show spontaneous self-propulsion and trajectories ranging from straight-line motion to destabilized motion with increasing Peclet number. We have performed studies with pinned active droplets which show only pumping mode and no self-propulsion. With increasing size, we see that in a dipolar field, the recirculating vortex pair initially at the back of the droplet moves to the front and later exhibits higher modes. We have characterized flow fields using particle image velocimetry and compared the observed flow fields with a Brinkman model showing an excellent agreement. Preliminary dual-channel measurements of filled micelle concentration and velocity field indicate a non-uniform reaction rate around the droplet circumference.