Various applications and natural processes involve large deformations and eventual breakup of liquid jets, layers, and droplets. When liquid masses fragment in a small number of pieces one speaks of breakup. More intense phenomena where, for instance, a liquid jet is broken into seemingly microscopic droplets are called atomization, although the term is somewhat incorrect, since the individual pieces are still far larger than atomic scales.

Nevertheless, atomization is a striking process in which finely divided sprays or droplet clouds are produced. This is often based on the ejection of a high-speed liquid jet from an atomizer nozzle. Many other configurations exist, such as sheets ejected at high speed from diversely shaped nozzles, or colliding with each other. As with many of the multiphase phenomena investigated in this book, atomization offers a rich physical phenomenology which is still poorly understood. Considerable progress has been made in the development of methods for atomization simulations during the last few years, and advances in hardware are making it possible to conduct simulations of unprecedented complexity.

Introduction

There are many important motivations for the study of spray formation, droplet breakup, and atomization. To take a first example from natural phenomena, spray formation atop ocean waves occurs when sufficiently strong winds strip droplets from the crests of the waves. Breaking waves also create bubbles that, when bursting at the surface, create a very fine mist that can rise high into the atmosphere.