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ISSN オンライン: 2642-0554

USING STRUCTURE INFORMATION IN MODELING OF MAGNETOHYDRODYNAMIC TURBULENCE

Ola Widlund
EPM-MADYLAM ENSHMG, B.P. 95 F-38402 St Martin d'Heres, France

要約

The properties of the magnetohydrodynamic turbulence closure proposed by Widlund et al (1998) are discussed for the case of homogeneous turbulence decaying in a static magnetic field (at low magnetic Reynolds numbers). The model is a Reynolds stress closure, extended with a transport equation for a dimensionality anisotropy variable α, which carries information about length scale anisotropy. The model is shown to be consistent with theory and experiments for both weak and strong magnetic fields. For the initial linear decay in strong magnetic fields, it produces the K ~ t−1/2 energy decay predicted by linear theory. When nonlinear effects are important, the model predicts an energy decay K ~ t−1.7 and length scale evolution in agreement with the experiments of Alemany et al (1979).