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Program
News October 14, 2004
The latest Program and CICLoPE description are now available
Summary
Interactions amongst several members of our group over the last few years motivated us to meet for a two-day workshop at Princeton
University in October of 2003. As researchers in the field of turbulence, with a recent focus on high Reynolds number flows, we have
not been satisfied with the rate of progress in this technologically important field of fluid dynamics. For example, we recognize that
while wall-bounded flows present a wonderful array of problems in turbulence, we have lately been bogged down by some controversies that
do not seem to have been resolved to everyone's satisfaction. Therefore, we have been motivated by the idea that effective and thorough
interactions could help us move beyond the current state of understanding. The workshops are organized to maximize discussion and
introspection with an atmosphere that encourages an open mind approach to the issues. During the workshops, enough time is planned for
each of us to convince others of what is right at the present level of understanding in the spirit of true intellectual inquiry. We
hope that out of these meetings will emerge a shared sense of understanding, and perhaps with a clearer sense of where our future
efforts should lie.
Background
Several recent experiments on zero pressure-gradient turbulent boundary layers (in USA, Sweden, Holland, and Australia) have yielded
ground-breaking results and have substantially modified the consensus about the so called log-layer constants. The values of these
constants or parameters are vital in drag predictions for airplanes and in many other engineering flow applications. Recent experiments
at relatively high Reynolds numbers in a plane turbulent channel flow (in Germany and USA) have also shown interesting similarities and
differences as compared to the boundary layer case. It appears as the log-layer constants in this flow are very close to those recently
determined in the boundary layer case. The third canonical case is that of turbulent flow in a cylindrical pipe. High Reynolds number
experiments have recently been carried out for this case in the USA. The facility is located at Princeton University and is known as
the ``superpipe.'' These experiments have attracted much attention both from a purely scientific viewpoint and from the viewpoint of
potential importance for engineering applications. The results exhibit a number of interesting similarities with the other canonical
cases, but also some distinct differences.
In the boundary layer and channel flow cases, conventional experimental facilities have been used, which readily allow a number of
different well tested experimental flow measurement techniques. In the superpipe experiments a high pressure (of about 200 atmospheres)
is used to achieve the high Reynolds numbers. This has been successfully implemented and measurements of mean velocity have been made
with Pitot tubes. Hot-wire measurements have also been used to obtain information on spectral density and fluctuation intensities. The
recent findings for the three canonical flows have triggered a series of highly interesting research issues about universality of
turbulence features in different regions of the flow near surfaces, in particular the so called overlap region. Of primary interest to
the scientific and engineering community is to complement the pipe flow experiments from the superpipe facility with new measurements at
high Reynolds numbers in a facility that would readily allow detailed flow structure measurements, and high resolution
turbulent-fluctuations measurements.
New computations with moderately high Reynolds number direct numerical simulations (from Spain USA and Japan), have also suggested a
role of the innner/outer layer interaction in wall-bounded flows that has not yet been fully understood or not mapped out in detail.
Well-planed high Reynolds number experiments can also play a crucial role here. In addition, the understanding of the differences in
the character of the outer layer between the three canonical flows is as yet incomplete and would require new high Reynolds number
experiments to be significantly advanced.
First Workshop
The first workshop was hosted by Professor Lex Smits at Princeton University on October 16 and 17, 2003. Its summary recommendations may
be found HERE.
Following the success of this workshop, the group agreed to gather for a
second meeting in approximately one year. All of the participants also agreed to support a new initiative that was proposed during one of
the presentations by Professor Arne Johansson. The central idea in the proposal is to form an international `consortium' or interest group
that would pursue the task of realizing a new high Reynolds number experiment with detailed flow measurements in a turbulent pipe flow. The
Reynolds number, based on centerline velocity and diameter, aimed for is 2.0-2.5 million. A potential facility location in Predappio, Italy,
has been identified in an initial investigation by representatives from Univ. of Bologna at Forli (Dean F. Persiani and Prof. A. Talamelli)
and KTH (Profs. H. Alfredsson and A. Johansson). The primary available space measures 120m x 10m x 8 m. We understand that initial steps
have been taken to secure relevant funding and initial design ideas are under development. Part of the activities at the second workshop
will involve further discussion of these plans and a possible visit to the at the ``Ex Industrie Caproni'' site in Predappio, Italy, in
coordination with the Universita' di Bologna at Forli. A document describing this possibility may be found HERE.
Second Workshop
The The Abdus Salam International Centre for Theoretical Physics has kindly agreed to offer free accommodation for all invited attendees.
Housing at the Centre's Adriatico Guest House will be available to the first 30 registrants, while others will be accommodated off-campus.
The Centre will also host a Group Dinner on Wednesday evening (November 6). All other costs will need to be borne by the participants.
Travelers from developing countries can write directly about travel support to the Centre Director, Professor K.R. Sreenivasan,
.
The program is now available
(Program). Please e-mail us about any questions
or comments; nagib@iit.edu or asmits@princeton.edu.
Participants
Participants in order of their affiliation:
Email list:
peter.monkewitz@epfl.ch, nagib@iit.edu, chris@admin.iit.edu, b.mckeon@imperial.ac.uk, j.morrison@ic.ac.uk, roddam@caos.iisc.ernet.in,
krs@ictp.trieste.it, jimenez@torroja.dmt.upm.es, juanc@torroja.dmt.upm.es, asmits@princeton.edu, gkunkel@princeton.edu, hal@mech.kth.se,
viktor@mech.kth.se, eaton@vonkarman.stanford.edu, odj@foi.se, fernholz@pi.tu-berlin.de, r.friedrich@lrz.tu-muenchen.de,
alessandro.talamelli@unibo.it, r-adrian@uiuc.edu, r-moser@uiuc.edu, min@unimelb.edu.au, mbjones@mame.mu.oz.au, marusic@aem.umn.edu,
hutchins@aem.umn.edu, renzo.piva@uniroma1.it, carlomassimo.casciola@uniroma1.it, rpanton@mail.utexas.edu, robert.mckee@swri.org,
kasagi@thtlab.t.u-tokyo.ac.jp, klewicki@mech.utah.edu, prof_noor_afzal@yahoo.com, jpmont@mame.mu.oz.au, f.nieuwstadt@wbmt.tudelft.nl,
tbn22@eng.cam.ac.uk, armenio@units.it, iwamoto@thtlab.t.u-tokyo.ac.jp, johansson@mech.kth.se, eaton@vk.stanford.edu,
wkgeorge@tfd.chalmers.se
Direct all correspondence
to: Alexander J. Smits
Department of Mechanical and
Aerospace Engineering
Princeton University, Princeton, NJ 08544
Tel: (609) 258 5117
Fax: (609) 258 2276
e-mail: asmits@princeton.edu
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