Proceedings Of The Iutam Symposium On Turbulent Non Turbulent Interface In Turbulent Shear Flows

Proceedings of the IUTAM Symposium on Turbulent/Non-Turbulent Interface in Turbulent Shear Flows

The turbulent/non-turbulent interface (TNTI) is an irregular boundary between turbulent and irrotational flow, which widely exists in various flow types, such as turbulent boundary layer, combustion flame front, turbulent patches in atmosphere and ocean, pollutant dispersion, etc. Due to its importance in affecting the intermittent characteristic and the mixing and entertainment process of turbulent flows, TNTI has become one of the most active branches of turbulent research in the past decades. Nevertheless, the scientific community still faces various challenges that hinder an ultimate characterization and modelling of TNTI. The unresolved problems, to name a few, spread from the lack of a well-accepted definition of TNTI to the intriguing origin of its fractal multi-scale nature. The dynamics of TNTI, which is the key for the mechanism of the exchange of mass, momentum and energy between turbulence and irrotational outflows, also deserves an interpretation from the perspective ofturbulent structures. This book presents the proceedings of the "IUTAM Symposium on turbulent/non-turbulent interface in turbulent shear flow' will be held in 2024, Oct. This book will collect the up-to-date works from active researchers worldwide to anchor the state-of-art knowledge of TNTI and to envision the future direction of this field. The focus includes but is not limited to the scaling for the geometries, kinematics and dynamics of TNTI, the role of turbulent structures in the entrainment process, multiphase flow with TNTI, high-fidelity turbulent model that accounts for the intermittency of TNTI, and reduce-order-model-based prediction for engineering application. The content is a valuable reference for researchers, engineers and students who are interested in understanding the complex behavior of TNTI in turbulent shear flows. This is an open access book.

IUTAM Symposium on Simulation and Identification of Organized Structures in Flows

The dynamics of transitional and turbulent flows is often dominated by organized structures with a life-time much longer than a characteristic time scale of the surrounding small-scale turbulence. Organized structures may appear as secondary flows as a result of an instability but they persist in turbulent flows. They manifest themselves as eddies or localized vortices and play an important role in e.g. mixing and transport processes. Al though the existence of organized structures has been revealed by many experiments and by numerical simulations they are somewhat elusive, as there is no consensus on how to define them and technically how to detect them. In recent years several identification tools for analysing complex flows have been developed. These tools include various versions of the Proper Orthog onal Decomposition (POD) technique, wavelet transforms, pattern recogni tion, etc. At the same time, improvements in experimental techniques have made available data that further necessitate efficient detection methods. A prominent example is the Particle Image Velocimetry (PIV) technique from which complex spatio-temporal flow data can be obtained. An interesting feature of some of the identification techniques is that they form the basis for reduced models by which dynamical processes can be studied in details. From studies of dissipative dynamical systems it has been revealed that, in phase space, transitional and turbulent flows can be identified by their low-dimensional behaviour. Thus, employing data from experiments or nu merical simulations to form modes residing on finite-dimensional attractors may dramatically reduce computing costs.

Proceedings of the Dynamic Flow Conference 1978 on Dynamic Measurements in Unsteady Flows