Global MHD Modelling of the ISM From large towards small scale turbulence.pdfVIP

Proceedings of The Magnetized Plasma in Galaxy Evolution Sep. 27th – Oct. 1st 2004, Jagiellonian University, Krak´ow, Poland Eds. K.T. Chy˙zy, R.-J. Dettmar, K. Otmianowska-Mazur and M. Soida Global MHD Modelling of the ISM - From large towards small scale turbulence Miguel A. de Avillez1,2 and Dieter Breitschwerdt1 1Institut f¨ur Astronomie, Universit¨at Wien, T¨urkenschanzstraße 17, A-1080 Wien, Austria 2 ´ ´ Department of Mathematics, University of Evora, R. Rom˜ao Ramalho 59, 7000 Evora, Portugal 5 0 Abstract 0 Dealing numerically with the turbulent nature and non-linearity of the physical processes 2 involved in the ISM requires the use of sophisticated numerical schemes coupled to HD and y MHD mathematical models. SNe are the main drivers of the interstellar turbulence by trans- a ferring kinetic energy into the system. This energy is dissipated by shocks (which is more M efficient) and by molecular viscosity. We carried out adaptive mesh refinement simulations (with a finest resolution of 0.625 pc) of the turbulent ISM embedded in a magnetic field with 4 mean field components of 2 and 3 µG. The time scale of our run was 400 Myr, sufficiently long to avoid memory effects of the initial setup, and to allow for a global dynamical equilibrium 1 to be reached in case of a constant energy input rate. It is found that the longitudinal and v transverse turbulent length scales have a time averaged (over a period of 50 Myr) ratio of 1 0.52-0.6, almost similar to the one expected for isotropic