二维瑞利-贝纳德对流中的混沌转变：磁场的作用
Transition to chaos in two-dimensional Rayleigh-Bénard convection: the role of the magnetic field
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中文总结 AI 辅助
探讨外部磁场对二维瑞利-贝纳德对流数值模拟的影响，先在无磁场时建立基线，再引入磁场研究其对混沌转变的作用。发现磁场使行波涡动力学增加，促使对流涡分裂，分析速度场揭示相关拓扑变化及磁涡磁重联现象。
中文摘要 AI 辅助
研究了外部施加磁场对二维瑞利-贝纳德对流（RBC）数值模拟的影响。首先在无磁场情况下研究RBC模型以建立基线，然后引入背景磁场并探讨其对混沌转变的影响。对于纯流体动力学情况和一系列约化瑞利数，系统呈现行波涡，经吸引子合并危机后变为混沌行波涡。施加磁场后，行波涡动力学出现显著增加，且磁场促使对流涡分裂/破裂，这可能是二维湍流转变机制，对流元胞结构被破坏。对速度场详细分析表明，鞍点与对流涡中心碰撞恢复系统原始拓扑，产生两个对称动力学涡，碰撞时磁涡因磁重联一分为二，此行为间歇性发生。
英文摘要
The impact of an externally imposed magnetic field on numerical simulations of two-dimensional Rayleigh-Bénard convection (RBC) is investigated. Initially, the RBC model is examined in the absence of a magnetic field to establish a baseline. Then, a background magnetic field is introduced, and its influence on the transition to chaos is explored. For the purely hydrodynamic case and a range of the reduced Rayleigh number, the system exhibits traveling rolls which, after an attractor-merging crisis, give way to chaotic traveling rolls. Upon imposing a background magnetic field, there is a notable increase in the occurrence of traveling roll dynamics. Furthermore, the presence of the magnetic field favors the splitting/breaking of convective rolls, indicating a possible mechanism for transition to two-dimensional turbulence, with the structure of the convection cell being disrupted. A detailed analysis of the velocity field reveals that the collision between a saddle point and the center of a convective roll restores the system's original topology, with two symmetric kinetic vortices. During this collision, a magnetic vortex splits in two as a result of a magnetic reconnection. This behavior occurs intermittently in time.
