Thursday 18 Oct 2012: Numerical Tests of a New Theory for Magnetohydrodynamic Turbulence
Joanne Mason - University of Exeter
Harrison 101 14:00-15:00
Magnetised turbulence plays an essential role in many problems in astrophysics, space physics, laboratory plasma physics and classical dynamo theory. Magnetohydrodynamics (MHD) provides the simplest theoretical framework for studying magnetised plasma turbulence. Significant advances in computational power over the last decade have led to numerical simulations becoming an extremely valuable resource. The numerical results are used to test competing theoretical models and to guide future progress. Indeed, the results of some recent high-resolution simulations of incompressible MHD turbulence in the presence of a strong background magnetic field have highlighted a number of deficiencies in our understanding of even the most fundamental issues. Recently, Boldyrev (Phys. Rev. Lett., 96, 115002) proposed a new phenomenological theory that aims to resolve the controversy. The key prediction is a process known as `scale-dependent dynamic alignment', whereby the velocity and magnetic field fluctuations tend to align within a small scale-dependent angle in the field-perpendicular plane.
In this talk I will introduce the new theory and describe the results of an extensive set of high-resolution numerical simulations that have been specially designed in order to test the new theoretical predictions.