Towards realistic models of magnetic field generation in planetary cores

建立行星核心磁场生成的真实模型

• 批准号: 2633290
• 金额: --
• 依托单位: University of Leeds
• 依托单位国家: 英国
• 项目类别: Studentship
• 财政年份: 2021
• 资助国家: 英国
• 起止时间: 2021 至 无数据
• 项目状态: 未结题
• 来源: https://gtr.ukri.org/projects?ref=studentship-2633290
• 关键词: Towards; realistic; models; magnetic; field

Convection-driven flows influenced by rotation are ubiquitous in planetary interiors, including the liquid cores of terrestrial bodies, the outer regions of gas giants and the convective regions of cool stars. These flows generate global-scale magnetic fields that can be observed remotely and hence provide unique insight into otherwise inaccessible regions of planets and stars. However, from a fluid dynamical perspective, modelling the rotating fluid dynamics in the deep fluid interiors of these bodies represents an outstanding challenge because of the rapid rotation rates (equivalent to Ekman numbers E < 10-10) and turbulent flow (Reynolds number Re > 108). Such extreme conditions cannot be modelled by direct 3D computer simulation and so complementary approaches are required. This project will combine theoretical and computational work to improve: 1) quasi-geostrophic (QG) models of core dynamics that exploit the rapidly rotating limit to reduce the (magneto)hydrodynamic equations to 2D; 2) an asymptotically reduced model of convection and magnetic field generation that is valid in the limit of rapid rotation. Systematic analysis and comparisons of these new models with existing 3D simulations and convection experiments conducted at UCLA will allow the turbulent dynamics and the role of magnetic fields to be analysed in hitherto inaccessible dynamical regimes with direct application to planetary interiors.

受旋转影响的对流驱动流在行星内部普遍存在，包括类地天体的液体核心、气态巨星的外部区域和冷恒星的对流区域。这些流产生可以远程观测的全球范围的磁场，从而提供对行星和恒星无法到达的区域的独特见解。然而，从流体动力学的角度来看，由于快速旋转速率（相当于埃克曼数 E < 10-10）和湍流（雷诺数 Re > 108）。这种极端条件无法通过直接 3D 计算机模拟进行建模，因此需要补充方法。该项目将结合理论和计算工作来改进：1）核心动力学的准地转（QG）模型，利用快速旋转极限将（磁）流体动力学方程简化为二维； 2）对流和磁场生成的渐近简化模型，在快速旋转的极限下有效。对这些新模型与加州大学洛杉矶分校现有的 3D 模拟和对流实验进行系统分析和比较，将能够在迄今为止无法实现的动力学机制中分析湍流动力学和磁场的作用，并直接应用于行星内部。