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NUMERICAL SIMULATIONS OF TWO-WAY COUPLED MAGNETIC DYNAMOS IN COMPLEX GEOMETRIES

Sasa Kenjeres
Transport Phenomena Section, Department of Chemical Engineering, Faculty of Applied Sciences, Delft University of Technology and J.M. Burgerscentrum for Fluid Mechanics, Delft, The Netherlands

Kemal Hanjalic
Department of Physics, Novosibirsk State University (NSU), 1, Pirogov Str., Novosibirsk, 630090, Russia; Faculty of Applied Sciences, Delft University of Technology (TU Delft), Building 58, Van der Maasweg 9, 2629 HZ, Delft, The Netherlands

Abstract

We report on hybrid numerical simulations of a turbulent magnetic dynamo. The simulated setup mimics the Riga dynamo experiment characterized by hydrodynamic Reynolds Re~3.5×106 and magnetic Reynolds number 15≤Rem≤20, Gailitis et al. (2000). The simulations were performed by simultaneous fully coupled solution of the transient Reynolds-Averaged Navier-Stokes (T-RANS) equations for the fluid velocity and turbulence field, and the direct numerical solution of the magnetic induction equations (DNS). This fully integrated hybrid T-RANS/DNS approach, applied in the finite-volume numerical framework with a multi-block-structured non-orthogonal geometry-fitted computational mesh, reproduced the mechanism of self-generation of a magnetic field in close accordance with the experimental records. In addition to the numerical confirmation of the Riga findings, the numerical simulations provided detailed insights into the temporal and spatial dynamics of flow, turbulence and electromagnetic fields and their reorganization due to mutual interactions, revealing the full four-dimensional picture of a dynamo action in the turbulent regime under realistic working conditions.