|The Lagrangian Frequency Spectrum of Magnetohydrodynamic Turbulence
|459, 6th International Conference of Numerical Modeling of Space Plasma Flows (ASTRONUM 2011)
|Müller, W.; Busse, A.; Gogoberidze, G.
|The Lagrangian frequency spectrum is obtained via the two-time correlation of velocity signals
measured along the trajectories of tracers passively advected by a turbulent flow. It is shown to be related to the
characteristic autocorrelation timescale of nonlinear turbulent
interaction and the associated cascade timescale.
This interesting connection allows to use the Lagrangian energy spectrum as a
diagnostic to identify weak and strong turbulence. As a consequence,
cascade phenomenologies which predict identical Eulerian
inertial-range scalings, a situation known from, e.g.,
magnetohydrodynamic turbulence permeated by a strong mean
magnetic field, can be distinguished.
The new approach is
successfully applied to high-Reynolds-number direct numerical
simulations of two- and three-dimensional incompressible MHD turbulence.