Instabilities and spin-up behaviour of a rotating magnetic field driven flow in a rectangular cavity

This study presents numerical simulations and experiments considering the flow of an electrically conducting fluid inside a cube driven by a rotating magnetic field (RMF). The investigations are focused on the spin-up, where a liquid metal (GaInSn) is suddenly exposed to an azimuthal body force gene...

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Bibliographic Details
Published in:Physics of fluids (1994) 2017-11, Vol.29 (11), p.114104
Main Authors: Galindo, V., Nauber, R., Räbiger, D., Franke, S., Beyer, H., Büttner, L., Czarske, J., Eckert, S.
Format: Article
Language:English
Subjects:
Computational fluid dynamics
Computer simulation
Conducting fluids
Data transmission
Fluid dynamics
Magnetic fields
Numerical prediction
Oscillating flow
Oscillations
Physics
Proper Orthogonal Decomposition
Rotation
Secondary flow
Simulation
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Summary:This study presents numerical simulations and experiments considering the flow of an electrically conducting fluid inside a cube driven by a rotating magnetic field (RMF). The investigations are focused on the spin-up, where a liquid metal (GaInSn) is suddenly exposed to an azimuthal body force generated by the RMF and the subsequent flow development. The numerical simulations rely on a semi-analytical expression for the induced electromagnetic force density in an electrically conducting medium inside a cuboid container with insulating walls. Velocity distributions in two perpendicular planes are measured using a novel dual-plane, two-component ultrasound array Doppler velocimeter with continuous data streaming, enabling long term measurements for investigating transient flows. This approach allows identifying the main emerging flow modes during the transition from stable to unstable flow regimes with exponentially growing velocity oscillations using the Proper Orthogonal Decomposition method. Characteristic frequencies in the oscillating flow regimes are determined in the super critical range above the critical magnetic Taylor number T a c ≈ 1.26 × 1 0 5 , where the transition from the steady double vortex structure of the secondary flow to an unstable regime with exponentially growing oscillations is detected. The mean flow structures and the temporal evolution of the flow predicted by the numerical simulations and observed in experiments are in very good agreement.
ISSN:1070-6631
1089-7666
DOI:10.1063/1.4993777