Energy transfers and magnetic energy growth in small-scale dynamo
KAUST DepartmentMechanical Engineering Program
Physical Sciences and Engineering (PSE) Division
Clean Combustion Research Center
Fluid and Plasma Simulation Group (FPS)
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AbstractIn this letter we investigate the dynamics of magnetic energy growth in small-scale dynamo by studying energy transfers, mainly energy fluxes and shell-to-shell energy transfers. We perform dynamo simulations for the magnetic Prandtl number Pm = 20 on 10243 grid using the pseudospectral method. We demonstrate that the magnetic energy growth is caused by nonlocal energy transfers from the large-scale or forcing-scale velocity field to small-scale magnetic field. The peak of these energy transfers moves towards lower wave numbers as dynamo evolves, which is the reason why the integral scale of the magnetic field increases with time. The energy transfers U2U (velocity to velocity) and B2B (magnetic to magnetic) are forward and local. Copyright © EPLA, 2013.
SponsorsWe thank K. SUBRAMANIAN for valuable discussions and comments, and RAKESH YADAV for performing the initial set of numerical simulations. We are grateful to the anonymous referees for comments and suggestions that helped us improve the manuscript. Our numerical simulations were performed on the IBM Blue Gene P "Shaheen" at KAUST supercomputing laboratory, Saudi Arabia. This work was supported through the Swarna-jayanti fellowship to MKV from Department of Science and Technology, India. RS was supported through baseline funding at KAUST.
JournalEPL (Europhysics Letters)