The study of droplets and sprays has developed rapidly over the past two decades because of their many important applications, from automobile engine combustion to drug aerosols. This book addresses the complex subject of the interactions of droplets and sprays. It describes the behavior of an individual droplet in a spray, the behavior of a spray, and the critical relationships between the two. Along with a strong theoretical foundation, the book presents results in a way that will be useful for engineering practice, with summaries of key formulae and examples of various spray computations. Among topics covered are transient heating (or cooling) and vaporization (or condensation), multicomponent liquid droplet vaporization, near critical and supercritical ambient conditions, interaction of droplets with turbulent or vortical structures, distortion of the spherical shape and secondary atomization of the droplets, and computational issues. As an authoritative review of the science and technology of droplets and sprays, this book will be useful for graduate students, researchers, and practicing engineers.