{
  "annotation_id": "7a65ed13-cd68-4af2-8707-6f40038bdf56",
  "date_created": "2026-03-02T18:01:07.019000Z",
  "date_modified": "2026-03-02T18:01:07.019000Z",
  "file_hash": "c5fbd1652731e5d2ee5c155163c4404a3454d5c05f5b4905b9863b0408ce3de4",
  "private": false,
  "record": {
    "abstract": "The role of turbulence in current generation and self-excitation of magnetic\nfields has been studied in the geometry of a mechanically driven, spherical\ndynamo experiment, using a three dimensional numerical computation. A simple\nimpeller model drives a flow which can generate a growing magnetic field,\ndepending upon the magnetic Reynolds number, Rm, and the fluid Reynolds number.\nWhen the flow is laminar, the dynamo transition is governed by a simple\nthreshold in Rm, above which a growing magnetic eigenmode is observed. The\neigenmode is primarily a dipole field tranverse to axis of symmetry of the\nflow. In saturation the Lorentz force slows the flow such that the magnetic\neigenmode becomes marginally stable. For turbulent flow, the dynamo eigenmode\nis suppressed. The mechanism of suppression is due to a combination of a time\nvarying large-scale field and the presence of fluctuation driven currents which\neffectively enhance the magnetic diffusivity. For higher Rm a dynamo reappears,\nhowever the structure of the magnetic field is often different from the laminar\ndynamo; it is dominated by a dipolar magnetic field which is aligned with the\naxis of symmetry of the mean-flow, apparently generated by fluctuation-driven\ncurrents. The fluctuation-driven currents have been studied by applying a weak\nmagnetic field to laminar and turbulent flows. The magnetic fields generated by\nthe fluctuations are significant: a dipole moment aligned with the symmetry\naxis of the mean-flow is generated similar to those observed in the experiment,\nand both toroidal and poloidal flux expulsion are observed.",
    "arxiv_id": "physics/0602126",
    "authors": [
      "R. A. Bayliss",
      "C. B. Forest",
      "M. D. Nornberg",
      "E. J. Spence",
      "P. W. Terry"
    ],
    "categories": [
      "physics.plasm-ph",
      "physics.flu-dyn"
    ],
    "doi": "10.1103/PhysRevE.75.026303",
    "title": "Numerical simulations of current generation and dynamo excitation in a   mechanically-forced, turbulent flow",
    "url": "https://arxiv.org/abs/physics/0602126"
  },
  "schema_id": "dorsal/arxiv",
  "source": {
    "execution_id": "0faaf0d0-4489-4ea7-b2a7-88db81c4afaa",
    "id": "arXiv Dataset IDs",
    "type": "Model",
    "variant": "snapshot-2026-03-01",
    "version": "0.1.0"
  },
  "user_id": 1000002
}