The book is the only one of its kind devoted entirely to the subject of Large Eddy Simulation. It presents a comprehensive account and a unified view of this young but very rich discipline. LES is the only efficient technique for approaching high Reynolds numbers when simulating industrial, natural or experimental configurations. The author concentrates on incompressible fluids. The topics are well chosen and both the mathematical ideas and the applications are presented with care. The book addresses researchers as well as graduate students and engineers. This second edition is a greatly enriched version motivated both by the increasing theoretical interest in LES and the increasing number of applications. Two entirely new chapters are devoted to the coupling of LES with multiresolution multidomain techniques and to the new hybrid approaches that relate the LES procedures to the classical statistical methods based on the Reynolds Averaged Navier - Stokes equations.