Electro-vortex flows in shallow liquid metal layers


Electro-vortex flows in shallow liquid metal layers

Kolesnichenko, I.; Khripchenko, S.; Buchenau, D.; Gerbeth, G.

We investigate different kinds of electro-vortex flows generated in a shallow layer of liquid metal. The metal flow is driven by an externally applied electrical current which interacts with its own magnetic field. Due to symmetry this interaction alone causes not yet a flow as the Lorentz force is purely irrotational. If, however, ferromagnetic C-cores or yokes are applied, the magnetic field distribution is modified and a flow driving action results. An electro-vortex flow occurs with several eddies in this MHD-layer. In the stable case, for some range of electrical current values, these eddies are held in permanent position. The unstable case is characterized by an oscillation of the eddies, which are moving in the plane of the layer. One of the reasons to perform this study is related with the occurrence of similar unstable processes in some devices used for metallurgical purposes including the flat MHD-layer considered here. We have investigated this flow by experimental and numerical methods.
We applied the ultrasound Doppler velocimetry which allows us to measure velocity profiles in non-transparent media. The oxide particles of this alloy were acting as good tracers for ultrasound measurements and allowed us to obtain the time-dependences of the velocity profiles. At higher electrical currents, the profiles showed large-scale low-frequency oscillations. Various types of flows are distinguished depending on the location of the ferromagnetic C-core.
The mathematical model of the processes was based on the MHD-equations, which have been modified using a thin-layer approximation. The numerical calculations support the results obtained in experiments, and showed the behavior of the velocity field with the moving of the eddies.

  • Contribution to proceedings
    Joint 15th Riga and 6th PAMIR International Conference on Fundamental and Applied MHD, 27.06.-01.07.2005, Jurmala, Latvia
    1(2005), 199-202
  • Poster
    Joint 15th Riga and 6th PAMIR International Conference on Fundamental and Applied MHD, 27.06.-01.07.2005, Jurmala, Latvia

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Publ.-Id: 7435