Effects of flow shear and Alfven waves on two-dimensional magnetohydrodynamic turbulence
- Department of Applied Mathematics, University of Sheffield, Sheffield, S3 7RH (United Kingdom)
- EURATOM/UKAEA Fusion Association, Culham Science Centre, Abingdon, OX14 3DB (United Kingdom)
The suppression of turbulent transport by large scale mean shear flows and uniform magnetic fields is investigated in two-dimensional magnetohydrodynamic turbulence driven by a small-scale forcing with finite correlation time. By numerical integration the turbulent magnetic diffusivity D{sub T} is shown to be significantly quenched, with a scaling D{sub T}{proportional_to}B{sup -2}{omega}{sub 0}{sup -5/4}, which is much more severe than in the case of a short or delta correlated forcing typified by white noise, studied in E. Kim and B. Dubrulle [Phys. Plasmas 8, 813 (2001)]. Here B and {omega}{sub 0} are magnetic field strength and flow shear rate, respectively. The forcing with finite correlation time also leads to much stronger suppression of momentum transport through the cancellation of the Reynolds stress by the Maxwell stress with a positive small value of turbulent viscosity, {nu}{sub T}>0. While fluctuating kinetic and magnetic energies are unaffected by the magnetic field just as in the case of a delta correlated forcing, they are much more severely quenched by flow shear than in that of a delta correlated forcing. Underlying physical mechanisms for the reduction of turbulent transport and turbulence level by flow shear and magnetic field are discussed.
- OSTI ID:
- 21120295
- Journal Information:
- Physics of Plasmas, Vol. 15, Issue 5; Other Information: DOI: 10.1063/1.2913270; (c) 2008 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); ISSN 1070-664X
- Country of Publication:
- United States
- Language:
- English
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