Thermoelectric precession in turbulent magnetoconvection
Thermoelectric precession in turbulent magnetoconvection
复制标题
湍流磁对流中的热电进动
DOI：
10.1017/jfm.2021.880
复制
发表时间：
2022
影响因子：
3.7
通讯作者：
Aurnou, Jonathan M.
中科院分区：
文献类型：
--
作者：
Xu, Yufan;Horn, Susanne;Aurnou, Jonathan M.
我们提出了热电流和湍流磁对流之间相互作用的实验室测量。在从下方加热、从上方冷却并受到垂直磁场作用的圆柱形液态镓中，发现大尺度环流（LSC）可以经历缓慢的轴向进动。我们的实验表明，这种 LSC 进动仅在采用导电边界条件时才会发生，并且当轴向磁场方向翻转时，进动方向会反转。开发了热电磁对流 (TEMC) 模型，成功预测了零级磁进动动力学。我们的 TEMC 磁进动模型取决于顶部和底部边界的热电电流回路，这会产生洛伦兹力，从而在翻转的大规模循环流上产生水平扭矩。我们模型中的热电扭矩用于驱动 LSC 的进动运动。该模型产生的进动频率预测与实验观察结果非常吻合。我们假设，对流流动中的热电效应长期以来被认为与液态金属传热和混合过程相关，也可能在行星内部磁流体动力学中得到应用。
We present laboratory measurements of the interaction between thermoelectric currents and turbulent magnetoconvection. In a cylindrical volume of liquid gallium heated from below and cooled from above and subject to a vertical magnetic field, it is found that the large-scale circulation (LSC) can undergo a slow axial precession. Our experiments demonstrate that this LSC precession occurs only when electrically conducting boundary conditions are employed, and that the precession direction reverses when the axial magnetic field direction is flipped. A thermoelectric magnetoconvection (TEMC) model is developed that successfully predicts the zeroth-order magnetoprecession dynamics. Our TEMC magnetoprecession model hinges on thermoelectric current loops at the top and bottom boundaries, which create Lorentz forces that generate horizontal torques on the overturning large-scale circulatory flow. The thermoelectric torques in our model act to drive a precessional motion of the LSC. This model yields precession frequency predictions that are in good agreement with the experimental observations. We postulate that thermoelectric effects in convective flows, long argued to be relevant in liquid metal heat transfer and mixing processes, may also have applications in planetary interior magnetohydrodynamics.