Transition from wall modes to multimodality in liquid gallium magnetoconvection

Coupled laboratory-numerical experiments of Rayleigh-Bénard convection in liquid gallium subject to a vertical magnetic field are presented. The experiments are carried out in two cylindrical containers with diameter-to-height aspect ratio Γ = 1.0 and 2.0 at varying thermal forcing (Rayleigh numbers...

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Bibliographic Details
Published in:Physical review fluids 2023-10, Vol.8 (10)
Main Authors: Xu, Yufan, Horn, Susanne, Aurnou, Jonathan M.
Format: Article
Language:English
Subjects:
CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS
Convection
Direct numerical simulations
Flow instability
High Hartmann number flows
Liquid metals
Magnetohydrodynamic turbulence
Magnetohydrodynamics
Navier-Stokes equation
Thermometry
Time series analysis
Transition to turbulence
Turbulence
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Summary:Coupled laboratory-numerical experiments of Rayleigh-Bénard convection in liquid gallium subject to a vertical magnetic field are presented. The experiments are carried out in two cylindrical containers with diameter-to-height aspect ratio Γ = 1.0 and 2.0 at varying thermal forcing (Rayleigh numbers 105 ≲ Ra ≲ 108) and magnetic field strength (Chandrasekhar numbers 0 ≲ Ch ≲ 3 × 105). Laboratory measurements and numerical simulations confirm that magnetoconvection in our finite cylindrical tanks onsets via nondrifting wall-attached modes, in good agreement with asymptotic predictions for a semi-infinite domain. With increasing supercriticality, the experimental and numerical thermal measurements and the numerical velocity data reveal transitions between wall mode states with different azimuthal mode numbers and between wall-dominated convection to wall and interior multimodality. These transitions are also reflected in the heat transfer data, which combined with previous studies connect onset to supercritical turbulent behaviors in liquid metal magnetoconvection over a large parameter space. The gross heat transfer behaviors between magnetoconvection and rotating convection in liquid metals are compared and discussed.
ISSN:2469-990X
2469-990X