Determination of anomalous exponents of structure functions in two-dimensional magnetohydrodynamic turbulence

H. Politano; A. Pouquet; V. Carbone

doi:doi:10.1209/epl/i1998-00391-2

DOI: 10.1209/epl/i1998-00391-2

Europhys. Lett, 43 (5), pp. 516-521 (1998)

Determination of anomalous exponents
of structure functions in two-dimensional
magnetohydrodynamic turbulence

H. Politano ¹, A. Pouquet ¹ and V. Carbone ²

¹ Laboratoire G.D. Cassini, CNRS UMR 6529, OCA Observatoire de Nice
B.P. 4229, 06304 Nice Cedex 04, France
² Dipartimento di Fisica, Università della Calabria
87036 Roges di Rende, Cosenza, Italy

(received 23 February 1998; accepted in final form 14 July 1998)

PACS. 47.27Jv - High-Reynolds-number turbulence.
PACS. 47.27Gs - Isotropic turbulence; homogeneous turbulence.
PACS. 47.65 ${\rm +a}$ - Magnetohydrodynamics and electrohydrodynamics.

Abstract:

We determine numerically in two space dimensions the anomalous exponents of structure functions of the velocity ${\bf v}$ , the magnetic field ${\bf b}$ and the Elsässer variables ${\bf z}^{\pm}={\bf v}\pm {\bf b}$ up to order eight. To that effect, we make use of new exact relationships derived recently for mixed ${\bf z}^{\pm}$ third-order correlators. These exponents are compared to existing models of intermittency for either neutral or MHD flows, none of which seem to apply, possibly indicative of a more complex behavior for MHD flows than for neutral fluids.

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