TURBCONC · Fundamental and conceptual aspects of turbulent flows

Final Activity Report Summary - TURBCONC (Fundamental and conceptual aspects of turbulent flows)

At present the major effort in turbulence - both in education / training and research - is concentrated around a great variety of problems of an applied nature. One of the main premises of the reported project is the view that without corresponding progress in education / training and research of fundamental nature there is little chance for real progress in most applications in which turbulence plays a central role. Basic aspects of turbulent flows are of primary interest not only from the point of scientific curiosity, but as a vital prerequisite that lie at the heart of innovation: new knowledge has proven economically and socially valuable, it results in a number of significant practical payoffs: there is a desperate need for physical fundamentals of essentially all applications. Fortunately, the recognition and concern for urgent necessity of far more intensive fundamental research becomes more visible, e.g. it got an emphatic expression during the meeting of the recipients of Marie Curie chairs at 14 February 2007 in Brussels. Hence the described research was designed in response to the urgent necessity to bring fundamental research into proportion with the applied research in turbulence. Thus the present project addressed a number of essential basic features of turbulent phenomena (rather than their numerous models) with the main emphasis on fundamental, conceptual and problematic aspects and physical phenomena, and critical analysis / assessment of the state of conceptual aspects. Education and training. In view of the need to intensify the fundamental aspects and to put more emphasis and priority for high level teaching and dissemination (i.e. highly qualified young personnel) the following activities were undertaken. Creation and delivery of extensive series of high-level lectures on conceptual basic aspects of turbulent flows in the Imperial College and in the frame of Wolfgang Pauli fellowship in Vienna as well as in a number of other European Universities; organisation of mini-courses for PhD's; initiation, organisation and leading scientific meetings; international turbulence seminar held in Imperial College London, 2006 - 2009 among others. Research The major general premises as described above defined the main issues of research. These consisted of two main ingredients: i) Comparative study of genuine and the so-called passive turbulence with the emphasis on the differences (as contrasted to similarities) in the evolution processes in genuine and passive turbulence such as the differences between vortex stretching and stretching of different but 'similar' passive vectors; ii) the field of velocity derivatives in turbulent flows, nonlocality of turbulence: coupling of small and large scales. The motivation for coping with such issues comes mainly from our previous experience showing that both issues are central in providing substantial insights in the essential physics of both genuine and 'passive' turbulence. The results of present project fully confirm this and point to further directions of research in fundamental and conceptual aspects of turbulent flows: one of the central conceptual objectives is to validate and further develop a new approach of studying turbulence as an 'undecomposable' whole. This includes definition, distinction, properties and mutual and bidirectional impact / coupling of conventionally defined inertial and dissipative ranges in turbulence at high Reynolds numbers, and sub-Kolmogorov resolution as a key means for coping with such problems with parallel employing Eulerian and Lagrangian settings. The bottom line is that due to distinctly basic nature of the project (both in education / training and research) a broad impact is expected on a multi- and inter-disciplinary scale, as turbulence plays an essential role in a large number of disciplines.

Data: CORDIS, © European Union