Large-Eddy Simulation (LES), which is an advanced eddy-resolving method for calculating turbulent flows, is used increasingly in Computational Fluid Dynamics, also for solving hydraulics and environmental flow problems. The method has generally great potential and is particularly suited for problems dominated by large-scale turbulent structures. This book gives an introduction to the LES method specially geared for hydraulic and environmental engineers. Compared with existing books on LES it is less theoretically and mathematically demanding and hence easier to follow, and it covers special features of flows in water bodies and summarizes the experience gained with LES for calculating such flows.The book was written primarily as an introduction to LES for hydraulic and environmental engineers, but it will also be very useful as an entry to the subject of LES for researchers and students in all fields of fluids engineering. The applications part will further be useful to researchers interested in the physics of flows governed by the dynamics of coherent structures.