Workshop :   Simulations of magnetohydrodynamic turbulence in astrophysics:
recent achievements and perspectives

Paris, France, 2 - 6 July 2001

Objective:
Numerical simulations are a powerful tool for the investigation of the complex physics of star formation and more generally of the interstellar matter. Magnetic field is ubiquitous in this medium and the motions are turbulent and supersonic. A huge number of degrees of freedom are coupled over several orders of magnitude in length scales, from the size of the super-clouds in the Galaxy ($>10^{20}$cm) to that of protostellar cores ($\sim 10^{16}$cm) and, likely even further, to the dissipative scales of the magneto-hydrodynamic (MHD) turbulence. Several teams worldwide have numerically addressed the properties of interstellar MHD turbulence, concentrating on either some aspects of the physics or on subranges of all the coupled scales. The first objective of this workshop will be a presentation and confrontation of the existing results and their points of agreement, with an emphasis on the open issues. In particular, the nature, origin and role of the coherent structures of the magnetic field which form in MHD turbulence (sheets, tubes, fibrillation of the field) is still not understood. In this regard, it can be of great interest to benefit from the expertise of researchers in the fields of solar convective turbulence as well as solar dynamo, topics where recent advances have been achieved. The second objective of this workshop will be a discussion of the next generation of numerical codes to be developed. Indeed, the present ones often use techniques that, for several reasons, will rapidly become insufficient for capturing both the multi-scale dynamics and the variety of discontinuities induced by shocks or thermal instabilities. The existence of localized regions of strong gradients is a situation where adaptive mesh refinement (AMR) techniques become essential. The development of such codes, which have also to be parallelized, requires the skills of specialized numericists. Some versions (MHD, 3D, AMR) already exist, have been made available to the community and have already brought results. We propose to have these codes and their capabilities presented to the astrophysical community in the perspective of adapting them to the complexity of the physics of interstellar turbulence.
 

Scientific organizing committee :
A. Brandenburg (Nordita, Copenhagen, Denmark),
E. Falgarone (Ecole Normale Supérieure & Observatoire de Paris, Paris, France) co-chair person,
C. Heiles (U.C. Berkeley, USA),
T. Passot (Observatoire de la Côte d'Azur, Nice, France) co-chair person,
Y. Ponty (Observatoire de la Côte d'Azur, Nice, France),
M. Proctor (DAMTP, Cambridge, UK),
A. Raga (UNAM, Mexico, Mexico),
M. Tagger (CEA, Saclay, France),
E. Vázquez-Semadeni (UNAM, Morelia, Mexico),
J.P. Zahn (Observatoire de Paris, Meudon, France),
E. Zweibel (U. Colorado, Boulder, USA).

Local organizing committee:
Marie Francoise Ducos
Edith Falgarone
Thierry Passot
Michel Perault
Annie Touchant

Main topics to be covered:
Numerical simulations of interstellar turbulence
Turbulent convection
Algorithms for high resolution simulations of MHD flows
Small-scale structures in MHD turbulence
Solar and galactic dynamos
Radiative shocks
Observational constraints on interstellar and solar turbulence and magnetic fields
Limits of the MHD approximation in  the context of ISM turbulence
 

Lectures:
Both plenary lectures (40' +10' for questions) and contributed papers ( 15'+ 5' for questions) are planned.
Posters will be on permanent display.

The invited lecturers are :

S. Balbus (U. Virginia, USA),  A. Bhattacharjee  (U. Iowa, USA), A. Brandenburg (Nordic Institute for Theoretical Physics, Denmark),
D. Clarke (Saint Mary's University, Halifax, Canada and LAOG, Grenoble, France),
R. Crutcher (NCSA, U. Illinois), R. Grauer (Institut fuer Theoretische Physik, Duesseldorf, Germany),
C. McKee (U.C. Berkeley, USA), M. Mac Low (American Museum of Natural History, New York, USA),
W. Matthaeus (U. Delaware, USA), A. Nordlund (Astronomical Observatory, Copenhagen, Denmark),
E. Ostriker (U. Maryland, USA), E. Vishniac (Johns Hopkins University, USA),
R. Walder (Institut fuer Astronomie, Zurich, Switzerland), U. Ziegler (Astrophysikalisches Institut Potsdam, Germany),
E. Zweibel (U. Colorado, Boulder, USA)

Registration:
To register to this workshop, please fill in the enclosed registration form by clicking here .

Contributed papers:
If you wish to submit a contributed paper, please send by email to passot@obs-nice.fr, no later than April 30th, 2001, an abstract in regular latex, not exceeding one printed page, and possibly including references.

Requests for financial support:
Young scientist support, intended for PhD students or recent PhD, will cover registration fees and part of accomodation.
Application for support must include a recommendation letter and a curriculum vitae. The deadline for financial support requests is March 30th.

Practical informations

Lodging

List of Participants

List of Abstracts

Scientific Program
 

The proceedings are now published in Springer Verlag

Organizers:
Edith Falgarone (edith@lra.ens.fr)     and    Thierry Passot (passot@obs-nice.fr)

Laboratoire de Radioastronomie,           Laboratoire Cassini
ENS - Departement de Physique,         Observatoire de la Côte d'Azur
24 rue Lhomond 75231 Paris Cedex 05,    BP 4229, 06304 Nice Cedex 4

Acknowledgments :

Programme National PCMI
GdR Turbulence
Laboratoire de Radioastronomie, ENS
Observatoire de Paris