The workshop ‘Direct and Large-Eddy Simulation-4’ was held at the Uni- versity of Twente, July 18-20, 2001. DLES4is part of a series of ERCOFf AC workshops that originated at the University of Surrey in 1994. Over the years the DLES-series has grown into a major international venue focused on the development and application of direct and large-eddy simulation. Fundamental turbulence – and modeling issues but also elements from modem numerical analysis are at the heart of this field of interest, a fact which is clearly reflected by the contents of these proceedings. Modeling and simulation of complex flow phenomena forms a central ele- ment in a large volume of scientific – and applied research. The problem of simulating turbulent flows and capturing their main dynamical features remains a highly motivating challenge. This three-day workshop focused on recent de- velopments in numerical and physical modeling of complex flow phenomena concentrating on modem strategies in the field of direct and large-eddy simula- tion. A major aim was to promote the exchange of ideas and problems from both industrial and academic background paying attention to physical, mathematical and engineering aspects.