NATO Advanced Study Institute

Flow and Transport Processes in Complex Obstructed Geometries

Kiev, May 4 - 15, 2004

The NATO Advanced Study Institute “Flow and Transport Processes in Complex Obstructed Geometries: from cities and vegetative canopies to engineering problems” took place in Kyiv, the capital of Ukraine, during May 4 May 12, 2004, (www.hydromech.kiev.ua). All the participants came to the conclusion that this scientific event was very successful. The present web site preserves the most important materials presented by NATO ASI participants. It is our hope that they may be of interest to other scientists working with flows of different kinds. This site may also serve as a meeting point in preparations to next conference devoted to flows in obstructed geometries.

At the time when the idea of this meeting on flows through vegetated layers was proposed, we did not expect that it would attract such wide interest. More than 80 scientists of every level of seniority were coming from 25 countries bringing with them a wide range of expertise and experience. This confirmed our initial belief that the theme of the meeting was indeed interdisciplinary and was of great practical importance for engineering and the environment.

Until recently the kind of flows discussed in our meeting had different names in different fields. Meteorologists called these "canopy flows" meaning air flows and transport of heat, moisture and gases and in forests or in agricultural plants. Meteorologists L. Allen, M. Budicko, R. Cionco, J. Cowan, A. Dubov, E. Inoue, A. Konstantinov, E. Lemon, G. Menzhulin, M. Raupach, R. Shaw, A. Thom together with wind engineers J. Cermak, R. Meroney, E. Plate were the first who investigated "obstructed flows" experimentally and theoretically. The advances made by meteorologists for vegetative canopies has recently been applied and extended to urban ecology, wind engineering, urban air quality (European programs TRAPOS and SATURN) and the dispersion of hazardous materials within complex obstructed geometries.

However, similar problems emerged in the study of hydraulics of vegetated channels or flood plains although were addressed quite independently. Their investigation was started by N. Kouwen, I. Nickitin, K. Kosorin, D. Knight, E. Pasche, S. Petryk and is now intensively going on by H. Nepf, I. Nezu, H. Stefan, T. Tsujimoto and other researchers. A flow interacting with a number of obstructions is important for many engineering applications. For example, the Institute of Hydromechanics of Ukrainian National Academy of Sciences has successfully applied this approach to performance of a unique spraying cooler of Zaporizhzhya nuclear plant (South Ukraine).

The disciplines cited above have produced a number of quite unusual results for turbulence and transport processes in obstructed flows. Applications of theory and experimental investigation of various flows through groups of obstructions, or, more generally, through penetrable roughnesses, include environmental problems of natural or agricultural canopies, ecological urban problems (reduction and prevention of the dispersion of hazardous materials in the event of a terrorist attack), water flows through vegetated beds in natural conduits and that during flood events, wind engineering problems, problems of industrial flows in heat exchangers etc. It has become evident that this research area occupies a relatively separate topic of fundamental fluid mechanics with applications in engineering and in environmental science. Recent advances in the field were also described and analyzed in the "Annual Review of Fluid Mechanics" (for instance, Finnigan J.J. Turbulence in Plant Canopies, 2000, 32; Britter R.E. and Hanna S.R. Flows and Dispersion in Urban Areas, 2003, 35), but have not yet been implemented in any textbooks. There was so a need to bring together experts from different disciplines in a scientific meeting with a strong interdisciplinary approach.

Many specialists of an outstanding level had come here to take part in our meeting either as key lecturers or participants. Although some of them have been carrying out their research for many years, more junior participants have presented the results of their doctoral theses. This involvement of the younger scientific generation is of vital importance for our science. The NATO Advanced Study Institute has been an excellent format to bring together experienced specialists and young researchers from various branches of fluid mechanics, in this case to deal with flow though different kinds of "canopies" in nature and in engineering. Our meeting provided an effective exchange of ideas and techniques. We are sure that it will give a great impetus to further research in these critical and challenging environmental and engineering problems.

This Internet side invites you to get acquainted with a number of valuable presentations made in Kyiv by key lecturers and participants. A number of photographs reveal the pleasure of the twelve scientifically intensive and non-formally communicative days in Kyiv in spring 2004.

The NATO ASI’s Organizational Committee expresses its gratitude to the NATO Scientific Affairs Division for making this meeting possible. We are thankful also to Dr. Omduth Coceal from the Reading University for his managing this valuable Internet resource.
Prof. Julian Hunt
 ASI director from NATO side
University College London, UK 		Prof. Victor Grinchenko
 ASI director from Ukrainian side
Institute of Hydromechanics of UNAS, Kyiv 		Prof. Yevgeny Gayev
 Executive ASI director
Institute of Hydromechanics of UNAS, Kyiv