Role of partial stable stratification on the onset of rotating magnetoconvection with a uniform horizontal field
Tirtharaj Barman, Arpan Das, Swarandeep Sahoo
备注：
After submission, we identified substantial issues in the manuscript that require major revision. In view of this, we believe it is appropriate to withdraw the current version from arXiv. We may consider resubmitting a corrected version in the future after proper revision
To explore the combined effects of partial thermal stable stratification and magnetic back-reaction within Earth's tangent cylinder, we study the onset of magnetoconvection in an infinite plane layer subject to horizontal magnetic field imposed perpendicular to the rotation axis. Three stratification models-fully unstable, weakly stable, and strongly stable-are considered to examine their influence on convective onset. A broad range of rotation rates and diffusivity ratios captures the effects of rotation and thermal-to-magnetic diffusivity contrast, while magnetic back-reaction is analyzed by varying the imposed magnetic field strength. To assess the impact of stratification on convection threshold and flow structure, we derive local scaling laws for critical onset parameters and compute penetration percentages to quantify convective intrusion into the stable layer. Results show that stable stratification promotes earlier onset and smaller-scale flows, with stronger effects in rotation-dominated regimes-hallmarks of penetrative convection. In weak magnetic fields, faster rotation enhances columnarity and intensifies stratification effects while delaying onset. Under strong magnetic fields, thicker rolls persist even at rapid rotation, with limited but noticeable penetration into the stable layer. Magnetic stabilization is more effective at low to moderate diffusivity ratios but weakens at high diffusivity ratio. Penetration decreases with stronger magnetic fields and rotation, especially under strong stratification, but varies non-monotonically with rotation in weak stratification and magnetic regimes. These findings highlight the complex interplay among stratification, rotation, and magnetic field strength in setting the onset and structure of rotating convection relevant to planetary interiors.
Direct numerical simulations and linear stability analysis are carried out to study mixed convection in a horizontal duct with constant-rate heating applied at the bottom and imposed transverse horizontal magnetic field. A two-dimensional approximation corresponding to the asymptotic limit of very strong magnetic field effect is validated and applied, together with full three-dimensional analysis, to investigate the flow's behaviour in the previously unexplored range of control parameters corresponding to typical conditions of a liquid metal blanket of a nuclear fusion reactor (Hartmann number…
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Scripps Institution of Oceanography, University of California San Diego（加州大学圣地亚哥分校斯克里普斯海洋研究所）；Jacobs School of Engineering, University of California San Diego（加州大学圣地亚哥分校雅各布工程学院）
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