1998/10/21 by G. Boffetta, Boffetta, G., Antonio Celani +5
Biochemistry, Genetics and Molecular Biology · Engineering · Physics and Astronomy · #Chaotic Dynamics (nlin.CD) #Characterization and Applications of Magnetic Nanoparticles #FOS: Physical sciences #Fluid Dynamics and Turbulent Flows #Geomagnetism and Paleomagnetism Studies #chao-dyn #nlin.CD
paper · pdf · doi:10.48550/arxiv.chao-dyn/9810026
6 pages RevTeX, 6 PostScript figures
arxiv created 1998/10/21 · openalex publication_date 1998/10/21 · arxiv updated 2009/11/30 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
The stability of a sheared magnetic field is analyzed in two-dimensional magnetohydrodynamics with resistive and viscous dissipation. Using a multiple-scale analysis, it is shown that at large enough Reynolds numbers the basic state describing a motionless fluid and a layered magnetic field, becomes unstable with respect to large scale perturbations. The exact expressions for eddy-viscosity and eddy-resistivity are derived in the nearby of the critical point where the instability sets in. In this marginally unstable case the nonlinear phase of perturbation growth obeys to a Cahn-Hilliard-like dynamics characterized by coalescence of magnetic islands leading to a final new equilibrium state. High resolution numerical simulations confirm quantitatively the predictions of multiscale analysis.