The structure of a turbulent reattaching flow behind a backward-facing step was studied experimentally in a low-velocity water channel, in order to observe the physical structure of the flow and to better understand the relation.

The Symposium on structure of Complex turbulent shear flows was proposed by the "Comite National Fran

The last two decades have witnessed an intensifying effort in learning how to manage flow turbulence: it has in fact now become one of the most challenging and prized techno logical goals in fluid dynamics. The goal itself is of course not new. More than a hundred years ago, Reynolds already listed factors conducive to laminar and to turbulent flow (including among them curvature and acceleration). Further more, it is in retrospect clear that there were several early instances ot successful turbulence management. Examples are the reduction in drag achieved with a ring-trip placed on the front of a sphere or the insertion of a splitter-plate behind a circular cylinder; by the early 1950s there were numerous exercises at boundary layer control. Although many of these studies were interesting and suggestive, they led . to no spectacularly successful practical application, and the effort petered out in the late 1950s. The revival of interest in these problems in recent years can be attributed to the emergence of several new factors. First of all, fresh scientific insight into the structure of turbulence, in particular the accumulated evidence for the presence of significant order in turbulent flow, has been seen to point to new methods of managing turbulence. A second major reason has been the growing realisation that the rate at which the world is consuming its reserves of fossil fuels is no longer negligible; the economic value of greater energy effi ciency and lower drag has gone up significantly.

Proceedings of the world renowned ERCOFTAC (International Symposium on Engineering Turbulence Modelling and Measurements).The proceedings include papers dealing with the following areas of turbulence:·Eddy-viscosity and second-order RANS models ·Direct and large-eddy simulations and deductions for conventional modelling ·Measurement and visualization techniques, experimental studies ·Turbulence control ·Transition and effects of curvature, rotation and buoyancy on turbulence ·Aero-acoustics ·Heat and mass transfer and chemically reacting flows ·Compressible flows, shock phenomena ·Two-phase flows ·Applications in aerospace engineering, turbomachinery and reciprocating engines, industrial aerodynamics and wind engineering, and selected chemical engineering problems Turbulence remains one of the key issues in tackling engineering flow problems. These problems are solved more and more by CFD analysis, the reliability of which depends strongly on the performance of the turbulence models employed. Successful simulation of turbulence requires the understanding of the complex physical phenomena involved and suitable models for describing the turbulent momentum, heat and mass transfer. For the understanding of turbulence phenomena, experiments are indispensable, but they are equally important for providing data for the development and testing of turbulence models and hence for CFD software validation. As in other fields of Science, in the rapidly developing discipline of turbulence, swift progress can be achieved only by keeping up to date with recent advances all over the world and by exchanging ideas with colleagues active in related fields.