论文标题
旋转磁磁体的过渡
Transitions in overstable rotating magnetoconvection
论文作者
论文摘要
已知经典的雷利 - 贝纳德对流（RBC）系统在存在或不存在旋转和/或磁场的情况下表现出亚临界或超临界的过渡。然而，到目前为止，尚未报道同时在平面层RBC中同时展示对流的亚临界和超临界分支，这取决于初始条件。在这里，我们报告了同时发生在均匀的水平磁场和垂直轴旋转的情况下，在垂直轴外旋转的情况下，在较低的电prandtl数量流体（液体金属）中同时出现对流的亚临界和超临界分支的现象。大量的三维（3D）直接数值模拟（DNS）和系统的低维建模，范围为$ 750 \ 750 \ leq \ Mathrm {ta} \ leq 3000 $和$ 0 <\ Mathrm {q} Chandrasekhar编号（$ \ Mathrm {Q} $，Lorenz Force的强度）令人信服地确立了现象。从DNS数据得出的简单三维模型的详细分叉分析表明，超临界的HopF分叉和传导状态的亚临界干草叉分叉对此负责。还详细探讨了prandtl编号对这些过渡的影响。
The classical Rayleigh-Bénard convection (RBC) system is known to exhibit either subcritical or supercritical transition to convection in the presence or absence of rotation and/or magnetic field. However, the simultaneous exhibition of subcritical and supercritical branches of convection in plane layer RBC depending on the initial conditions, has not been reported so far. Here, we report the phenomenon of simultaneous occurrence of subcritical and supercritical branches of convection in overstable RBC of electrically conducting low Prandtl number fluids (liquid metals) in the presence of an external uniform horizontal magnetic field and rotation about the vertical axis. Extensive three dimensional (3D) direct numerical simulations (DNS) and low dimensional modeling of the system, performed in the ranges $750 \leq \mathrm{Ta} \leq 3000$ and $0 < \mathrm{Q} \leq 1000$ of the Taylor number ($\mathrm{Ta}$, strength of the Coriolis force) and the Chandrasekhar number ($\mathrm{Q}$, strength of the Lorenz force) respectively, establish the phenomenon convincingly. Detailed bifurcation analysis of a simple three dimensional model derived from the DNS data reveals that a supercritical Hopf bifurcation and a subcritical pitchfork bifurcation of the conduction state are responsible for this. The effect of Prandtl number on these transitions is also explored in detail.
