Isaac Newton Institute for Mathematical Sciences

Turbulence

January - June 1999

Organisers: GF Hewitt (Imperial College), PA Monkewitz (Lausanne), N Sandham (QMW), JC Vassilicos (Cambridge)

Programme theme

Turbulence has long been acknowledged as one of the great-unsolved scientific and even conceptual problems of our time. But is it one problem or many?

Many similarities observed in different chaotic, multi-scale flows have led scientists to group these under the single heading 'turbulence', but there is, as yet, little theoretical basis for proposing turbulence as some universal natural state.

Turbulence occurs in industrial processes as well as in the oceans, the atmosphere of the Earth and other planets and in many astrophysical contexts. Turbulence occurs also in biological contexts, e.g. in humans, animals and even some plants. Engineers need to understand turbulent flows in order to control them, design for their adverse effects or utilise them to best effect (as in mixing processes). In all cases prediction is a necessary element in the engineering design calculations.

The development over the past 10-20 years of useable Computational Fluid Dynamics (CFD) codes has produced a sea change in the design and development approach, allowing products to be brought to the market much more rapidly and economically. However, CFD codes are necessarily based on turbulence models whose parameters have to be deduced from measurements. The generality of these parameters is questionable, and the mathematical aspects of the models have been inadequately explored.

Turbulence and turbulent-like phenomena are also of great interest as problems in mathematics and theoretical physics; and some of the mathematical and physical concepts that have been developed in these studies are being applied in other areas of mathematical sciences, especially the study of processes involving a combination of ordered and chaotic phenomena.

The practical importance of turbulence led the Royal Academy of Engineering to launch an Initiative on Turbulence, the most important outcome of which was the definition and agreement of this Newton Institute Research Programme. The main aim of the programme is to bring together the mathematics and engineering communities involved in the area to address the many problems and to map out future strategy.

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