Analysis of Drop Collisions

Abstract

When do droplets merge and when do they bounce? Over the last 10 years, advances in experimental techniques, such as high-speed cameras, have enabled us to make important discoveries on how the dynamics of thin gas films can influence the behaviour of liquid droplets. However, the exact physical mechanisms governing these phenomena are a subject of debate, leading to a variety of theoretical, experimental and computational approaches. In this document, I will study two problems: the head-on collision of two droplets, and the impact of a drop on a solid surface. I will outline the conventional fluid mechanical description, how it fails, and various candidates for the ``missing physics''.