Rapid advances in Direct Numerical Simulation (DNS) and Large Eddy Simulation (LES) of turbulence provide opportunities for improved prediction of incompressible and compressible turbulent flows. The book includes five invited and thirty-eight contributed papers presented at the Second AFOSR International Conference on DNS and LES held at Rutgers - The State University of New Jersey, on June 7-9, 1999. A broad range of topics in DNS and LES are presented, including new developments in LES modeling, numerical algorithms for LES and DNS, DNS and LES of reacting flows, and DNS and LES for supersonic and hypersonic boundary layers. The book provides a extensive view of the state of the art in DNS and LES.