Collisions of micron-sized charged water droplets in still air

Abstract

We show that fixed points and their stable manifolds determine collision outcomes of oppositely charged water droplets settling in still air. For droplets with large enough opposite charges, the stable manifold of a saddle forms a separatrix that divides colliding trajectories from those that do not collide. A consequence of our findings is that for large charges, collision outcomes are not sensitive to the breakdown of hydrodynamics at small distances.