Investigation into the dual role of shear flow in 2D MHD turbulence

The turbulent diffusion ηT of a large-scale magnetic field B0 is numerically studied in two-dimensional magnetohydrodynamic turbulence with an imposed shear flow. We demonstrate that a shear flow plays a dual role, quenching transport through shear destruction and enhancing it via resonance. Specifically without resonance ηT B0-4 with no shear (rms shearing rate=Ω=0) and ηT Ω-2.7 for B0=0, while with resonance ηT B0-2 Ω-2. These results indicate that the absence of resonance is responsible for the most catastrophic reductions in transport.