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arXiv · 1905.13688

Heat transfer and flow regimes in quasi-static magnetoconvection with a vertical magnetic field

Ming Yan·Michael A. Calkins·Stefano Maffei·Keith Julien·Steven M. Tobias·Philippe Marti
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Abstract

Numerical simulations of quasi-static magnetoconvection with a vertical magnetic field are carried out up to a Chandrasekhar number of $Q=10^8$ over a broad range of Rayleigh numbers $Ra$. Three magnetoconvection regimes are identified: two of the regimes are magnetically-constrained in the sense that a leading-order balance exists between the Lorentz and buoyancy forces, whereas the third regime is characterized by unbalanced dynamics that is similar to non-magnetic convection. Each regime is distinguished by flow morphology, momentum and heat equation balances, and heat transport behavior. One of the magnetically-constrained regimes appears to represent an `ultimate' magnetoconvection regime in the dual limit of asymptotically-large buoyancy forcing and magnetic field strength; this regime is characterized by an interconnected network of anisotropic, spatially-localized fluid columns aligned with the direction of the imposed magnetic field that remain quasi-laminar despite having large flow speeds. As for non-magnetic convection, heat transport is controlled primarily by the thermal boundary layer. Empirically, the scaling of the heat transport and flow speeds with $Ra$ appear to be independent of the thermal Prandtl number within the magnetically-constrained, high-$Q$ regimes.

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Ming Yan, Michael A. Calkins, Stefano Maffei, Keith Julien, Steven M. Tobias, Philippe Marti. 2019-08-29. Heat transfer and flow regimes in quasi-static magnetoconvection with a vertical magnetic field. https://doi.org/10.1017/jfm.2019.615

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