Dispersed multiphase flows are at the heart of many geophysical, environmental, industrial, and energy applications. Volcanic eruptions, rain formation, powder snow avalanches, sediment transport, and dust storms are some classic examples from the environment, while industrial applications include fluidized beds, slurry transport, fuel injection, cyclone separators, and plasma coating, to name a few. Although each application is unique, they share significant commonalities in the underlying dispersed multiphase-flow physics that govern their dynamics. This book takes a rigorous approach to explaining the complex interconnected physical processes that are at play, before developing different classes of mathematical models and numerical techniques that are appropriate for different regimes of dispersed multiphase flows. Containing many examples and over 100 exercises, it is suitable for use as a graduate-level textbook as well as a reference for researchers who want to model and simulate a multiphase flow phenomenon in their application.