The intracluster medium (ICM) is a tenuous plasma between galaxies. Long parallel strands of strong magnetic fields are seen in the ICM. These movies show the development of turbulence and the growth of magnetic fields in a numerical model of magnetohydrodynamic (MHD) turbulence. The computational model was ideal Isothermal MHD. The flow was computed in a periodic box on a uniform 1024 x 1024 x 1024 mesh. The velocity field was continually stirred with random long wavelength sine wave accelerations, which mimics the effect of changing gravitational field due to galaxies moving in the cluster. The B-field was initially uniform and very weak, with the magnetic pressure one million times weaker than gas pressure. Over the span of the simulation, the magnetic pressure increased to about 5% of the gas pressure and was strong enough to strongly influence the flow. The numerical simulation was run on the Minnesota Supercomputer Institute’s Mesabi cluster: using 22 compute nodes (two Intel Haswell 12-core Processors per node) for 44 hours.
Movies show the development of MHD turbulence in this system in terms of the magnetic and velocity fields. The magnetic energy density shows regions of strong magnetic field. The square of the vorticity field (or enstrophy density) shows regions of strong fluid shear such as slip surfaces and vortex tubes.