CMG - Geophysical Turbulence Program Workshop
Modeling Magnetohydrodynamic Turbulence
Application to planetary and stellar dynamos
at the National Center for Atmospheric Research (NCAR), Boulder, CO USA
Dates: June 27 to 30 2006
The National Center for Atmospheric Research
1850 Table Mesa Dr.
Boulder, Colorado, USA
Main Seminar Room
- David Montgomery (Dartmouth College)
- Annick Pouquet (NCAR/GTP)
- Paul Roberts (Unverstiy of California at Los Angeles)
The National Center for Atmospheric Research will host a workshop in
Boulder, Colorado, June 27-30, 2006 sponsored by the Geophysical Turbulence
Program (GTP) of the Institute for Mathematics Applied to Geosciences (IMAGe).
The workshop will bring together researchers using different approaches to the
understanding of MHD turbulence in general and to the generation of magnetic
fields (the dynamo process) with particular emphasis on the geo-dynamo and
other flows at low magnetic Prandtl number. The approaches considered are
modeling, experiments, theory and direct numerical simulations.
One of the most persistent difficulties in the computation of the turbulent behavior of
fluids and magnetofluids is the wide range of dynamically interacting length and
time scales that may have to be evaluated. At large Reynolds number, many
orders of magnitude in length scales are implied. Indeed, we observe a great variety
of scales in the dynamical behavior of the atmosphere and oceans, in hurricane
dynamics, in the solar wind, and the Sun, to cite some familiar examples.
For many purposes, it might be adequate to compute only the long-wavelength
components of the spectra of the fields involved if some more economical representation
or model of the small-scale behavior could be provided which would not adversely affect
the accuracy with which the large scales are computed. Such topics as "large eddy simulation"
and "eddy viscosity," designed to cope with this difficulty, have generated a vast literature,
but there is also the more difficult problem of obtaining a clear physical understanding
of the nature of these approximations as well as extending them to more complex
fluids than the ones they were first derived for in the context of fluid dynamics.
Moreover, the generation of the magnetic fields observed in many celestial bodies often
occurs in media for which the viscosity ν and the magnetic diffusivity
η are vastly different. For example, in the interstellar medium,
the magnetic Prandtl number PM = ν/η
can be as large as 1014, whereas in stars such as the Sun and for planets
such as Earth, it can be very low (lower than 10-5, the value for the Earth
fluid core); similarly, in liquid breeder reactors and in laboratory experiments with
liquid metals, we have PM << 1.
Mores scales must therefore be resolved, suggesting that more regimes at different
scales may arise.
The workshop will be organized mainly around invited talks and discussions, in which the
speakers will discuss the various approaches to these topics.
Sessions are planned on modeling turbulent flows and theoretical, experimental and
numerical issues in MHD turbulence and dynamos, with a special emphasis on the geo-dynamo.
Contributions may also be made by participants in poster form,
or time permitting an oral presentation (see Abstract Submission
for more information).
To register for the workshop, please visit the Registration
Eric Blackman, University of Rochester
Axel Brandenburg, Nordic Institute for Theoretical Physics
Daniele Carati (Université Libre de Bruxelles)
Ulrich Christensen, Max-Planck-Institut fur Aeronomie, Lindau
Mausumi Dikpati, NCAR
Cary Forest, University of Wisconsin
Agris Gailitis, University of Latvia, Riga
Gary Glatzmaier, University of California at Santa Cruz
Darryl Holm, Imperial College
Chris Jones, University of Leeds
Daniel Lathrop, University of Maryland
William Matthaeus, Bartol Research Institute
Charles Meneveau, Johns Hopkins University
Pablo Mininni, NCAR
David Montgomery, Dartmouth College
Aake Nordlund, Niels Bohr Institute
Jean-François Pinton, Ecole Normale Supérieure de Lyon
Hélène Politano, Observatoire de la Côte d'Azur, Nice
Yannick Ponty, Observatoire de la Côte d'Azur, Nice
Andy Soward, University of Exeter
Juri Toomre, University of Colorado
This workshop is co-sponsored by NSF CMG Grant #ATM-0327888