Oscillatory states in thermal convection of a paramagnetic fluid in a cubical enclosure subjected to a magnetic field gradient

Journal article (2012)
Department
MSP/Multi-Scale Physics (AS) (TU Delft)
Copyright: American Physical Society
DOI: https://doi.org/doi:10.1103/PhysRevE.85.046312
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Published Date

20-04-2012

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Source:

Physical Review E, 85 (4), 2012

Faculty

Applied Sciences

Department

MSP/Multi-Scale Physics

Abstract

We report experimental and numerical studies of combined natural and magnetic convection of a paramagnetic fluid inside a cubical enclosure heated from below and cooled from above and subjected to a magnetic field gradient. Values of the magnetic field gradient are in the range 9?|grad|b0|2|?900 T2/m for imposed magnetic field strengths in the center of the superconducting magnet bore of 1?|b0|max?10 T. Very good agreement between experiments and simulation is obtained in predicting the integral heat transfer over the entire range of working parameters (i.e., thermal Rayleigh number 1.15×105?RaT?8×106, Prandtl number 5?Pr?700, and magnetization number 0???58.5). We present a stability diagram containing three characteristic states: steady, oscillatory (periodic), and turbulent regimes. The oscillatory states are identified for intermediate values of Pr (40?Pr?70) and low magnetic field (|b0|max?2 T). Turbulent states are generated from initially stable flow and heat transfer regimes in the range of 70?Pr?500 for sufficiently strong magnetic field (|b0|max?4 T).