Parallel CFD 2008, the twentieth in the high-level international series of meetings featuring different aspect of parallel computing in computational?uid dynamics and other modern scienti?c domains was held May 19?22, 2008 in Lyon, France. The themes of the 2008 meeting included the traditional emphases of this c- ference, and experiences with contemporary architectures. Around 70 presentations were included into the conference program in the following sessions: Parallel Algorithms and solvers Parallel performances with contemporary architectures Structured and unstructured grid methods, boundary methods software framework and components architecture CFD applications(Bio ?uid, environmentalproblem)Lattice Boltzmannmethodand SPH Optimisation in Aerodynamics This book presents an up-to-date overviewof the state of the art in Parallel C- putational Fluid Dynamics from Asia, Europe, and North America. This reviewed proceedingsincluded about sixty percent of the oral lectures presented at the conf- ence. The editors. VI Preface Parallel CFD 2008 was organized by the Institut Camille Jordan of the Univ- sity of Lyon 1 in collaboration with the Center for the Development of the Parallel Scienti?c Computing. The Scienti?c Committee and Local Organizers of Parallel CFD 2008 are - lighted to acknowledge the generous sponsorship of the following organizations, through ?nancial or in-kind assistance. Assistance of our sponsors allowed to - ganize scienti?c as well as social program of the conference.