Dynamics of decaying two-dimensional magnetohydrodynamic turbulence

Journal Article · Sun Oct 01 00:00:00 EDT 1989 · Physics of Fluids B: Plasma Physics; (USA)

DOI:https://doi.org/10.1063/1.859060· OSTI ID:5336612

Biskamp, D; Welter, H ^[1]

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1. Max-Planck-Institut fur Plasmaphysik, EURATOM Association, 8046 Garching bei Munchen, Federal Republic of Germany (DE)

High-resolution numerical studies of decaying two-dimensional magnetohydrodynamic turbulence were performed with up to 1024{sup 2} collocation points in general periodic systems using various initial states, but restricting consideration to weak velocity-magnetic field correlation {rho}. The global evolution is self-similar with constant kinetic to magnetic energy ratio {ital E}{sup {ital V}}/{ital E}{sup {ital M}}, macro- and microscale Reynolds numbers, and correlation {rho}, while the total energy decays as {ital E}({ital t}){proportional to}({ital t}+{ital t}{sub 0}){sup {minus}1}. As in three dimensions, dissipative small-scale turbulence adjusts in such a way as to make the energy dissipation rate {epsilon} independent of the collisional dissipation coefficients. Normalized energy spectra are also invariant. The spectral index in the inertial range is, in general, close to 3/2 in agreement with Kraichnan's Alfven wave argument {ital E}{sub {ital k}} ={ital DB}{sup 1/2}{epsilon}{sup 1/2}{ital k}{sup {minus}3/2}, {ital B}=({ital E}{sup {ital M}}){sup 1/2}, {ital D}{congruent} 1.8{plus minus}0.2, but may be close to 5/3 in transient states, in which turbulence is concentrated in regions of weak magnetic field. In the dissipation range, intermittency gives rise to a modified dissipation scale {ital l}{sub eff} =({ital l}{sup 2}{lambda}){sup 1/3}, with {ital l}=Kolmogorov scale and {lambda}=Taylor microscale. This reflects the intermittency of the dissipation process, which is consistent with the picture of current microsheets of thickness {ital l} and width and spacing {lambda}.

• OSTI ID: 5336612
• Journal Information: Physics of Fluids B: Plasma Physics; (USA), Vol. 1:10; ISSN 0899-8221
• Country of Publication: United States
• Language: English

Related Subjects

75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
FLUIDS
TURBULENCE
COLLISIONAL PLASMA
ENERGY LOSSES
ENERGY SPECTRA
INVARIANCE PRINCIPLES
MAGNETIC FIELDS
MAGNETOHYDRODYNAMICS
NUMERICAL SOLUTION
OSCILLATION MODES
RESOLUTION
REYNOLDS NUMBER
TRANSIENTS
TWO-DIMENSIONAL CALCULATIONS
FLUID MECHANICS
HYDRODYNAMICS
LOSSES
MECHANICS
PLASMA
SPECTRA
640410* - Fluid Physics- General Fluid Dynamics