This book is one of three volumes entitled "ECARP-European Computational Aerodynamics Research Project", which was supported by the European Union in the Aeronautics Area of the Industrial and Materials Technology Programme. This volume contains optimization techniques for a number of inviscid and viscous problems like drag reduction, inverse, multipoint, wing-pylon-nacelle and riblets (Part A); and methodologies for solving the Navier Stokes equations on parallel architectures for compressible viscous flows in two and three dimensions (Part B).The main objective of this book is to disseminate information about cost effective methodologies for practical design problems and parallel CFD to be used by computer scientists and multidisciplinary engineers.