This book can be used as a reference for the topic of turbulence modeling, especially in an engineering modeling and simulation course or as a tool for professionals on practical applications. Turbulent flow modeling has many applications in industry. The relevant numerical methods have advanced to the level that could be used by industry professionals to model many natural turbulent flows with acceptable accuracy. In this book we cover the fundamentals of turbulence, modeling techniques, and algorithms (including RANS) available in COMSOL[registered] as well as providing several modeling examples and instructions for building these models. The companion DVD includes models and figures discussed in the book. It explains the physics and principles of turbulence and provides modeling examples using COMSOL.