The impact of droplets on plane liquid surfaces

A survey is provided of the wide variety of physical processes that can be observed during the impact of droplets on plane liquid surfaces. A particular process of drop impact depends on the detailed circumstances under which a collision takes place. Therefore, the impact of different branches of fluid mechanics on droplet impact will be discussed. Of great importance are the inertia of the approaching drop and surface tension effects. In some cases the compressibility, the viscosity of the liquid and capillarity are also important. Furthermore, the unsteadiness inherent to the process of drop impact can lead to the occurrence of kinematic effects. The significance of these properties to the various results of impinging drops is addressed