Influence of an external magnetic field on forced turbulence in a swirling flow of liquid metal
arXiv:0908.3821 · doi:10.1063/1.3194304
Abstract
We report an experimental investigation on the influence of an external magnetic field on forced 3D turbulence of liquid gallium in a closed vessel. We observe an exponential damping of the turbulent velocity fluctuations as a function of the interaction parameter N (ratio of Lorentz force over inertial terms of the Navier-Stokes equation). The flow structures develop some anisotropy but do not become bidimensional. From a dynamical viewpoint, the damping first occurs homogeneously over the whole spectrum of frequencies. For larger values of N, a very strong additional damping occurs at the highest frequencies. However, the injected mechanical power remains independent of the applied magnetic field. The simultaneous measurement of induced magnetic field and electrical potential differences shows a very weak correlation between magnetic field and velocity fluctuations. The observed reduction of the fluctuations is in agreement with a previously proposed mechanism for the saturation of turbulent dynamos and with the order of magnitude of the Von Karman Sodium dynamo magnetic field.
arXiv comment34 pages, 20 figures
References in corpus (4)
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- On the magnetic fields generated by experimental dynamos
- Large-scale intermittency of liquid-metal channel flow in a magnetic field
- Reduction of velocity fluctuations in a turbulent flow of gallium by an external magnetic field