Dynamics of zonal flows in planetary interiors and core-mantle interactions

行星内部纬向流动力学和核-地幔相互作用

• 批准号: 355636-2013
• 负责人: Dumberry, Mathieu
• 金额: $ 2.4万
• 依托单位: University of Alberta
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2017
• 资助国家: 加拿大
• 起止时间: 2017-01-01 至 2018-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=634073
• 关键词: Dynamics; zonal; flows; planetary; interiors

The focus of my research is on the dynamics of fluid planetary interiors and on core-mantle interactions in terrestrial planets. These are key elements in the evolution of planets and explain why, within our solar system alone, each planet has had a markedly different history. In this proposal, my research group will address using advanced computational models topics that range from understanding variations in the length of the Earth's day through to complex fluid behavior seen in the atmospheres of the giant planets. Planetary rotation is the dominant dynamical influence on flows inside planets. Flows in rapidly rotating planets exhibit a remarkable (and unintuitive) behavior: they tend to have no velocity variation in the direction parallel to the rotation axis. A displaced parcel of fluid will entrain with it every parcels above and below in a vertical column: the flow behaves as if it is only two-dimensional (2D). In my research group, we exploit this feature and simulate planetary flows using a 2D model of the dynamics. This allows us to study more turbulent regimes. In this research proposal, we will apply these ideas to simulate the zonal jets that are observed on Jupiter. We also apply this concept to simulate flows in the Earth's core, more specifically to study a class of flow that consists of differential motion between co-centric cylinders aligned with the rotation axis. Flows in Earth's core also interact with its solid boundaries at the top (mantle) and bottom (inner core). These interactions include electromagnetic (EM) coupling; one of my projects is to investigate the role that non-uniform EM coupling at the core-mantle boundary may have on the geometry of the magnetic field and its time variations observed at the Earth's surface. In addition, fluid-solid interactions produce changes in the rotation rates of the inner core and mantle: the latter are observed as changes in the length of day (LOD). One of my projects proposes to test different scenarios of core-mantle interactions with a goal to identify the nature of the force responsible for the changes in the LOD over the past 100 years.

我的研究重点是流体行星内部的动力学和类地行星的核-地幔相互作用。这些都是行星演化的关键元素，并解释了为什么仅在我们的太阳系内，每颗行星的历史就明显不同。在这个提案中，我的研究小组将使用先进的计算模型来解决各种主题，从理解地球一天的长度变化到在巨型行星的大气层中看到的复杂的流体行为。行星自转是影响行星内部流动的主要动力因素。快速旋转的行星中的流动表现出一个显著的(和不直观的)行为：它们在平行于旋转轴的方向上往往没有速度变化。一个移动的流体小块会将上下的每个小块卷在一个垂直柱中：流动的行为就好像它只是二维的(2D)。在我的研究小组中，我们利用这一特征，使用动力学的2D模型来模拟行星流动。这使我们能够研究更动荡的政权。在这项研究计划中，我们将应用这些想法来模拟在木星上观察到的纬向喷流。我们还将这一概念应用于模拟地核中的流动，更具体地说，是研究一类由沿旋转轴排列的同心圆柱体之间的差异运动组成的流动。地核中的流动也与其顶部(地幔)和底部(内核)的固体边界相互作用。这些相互作用包括电磁(EM)耦合；我的项目之一是研究在核-地幔边界的非均匀EM耦合可能对在地球表面观察到的磁场的几何形状及其时间变化所起的作用。此外，流固相互作用会导致内核和地幔的自转速度发生变化：后者是通过日长(LOD)的变化观察到的。我的一个项目提议测试不同的核-地幔相互作用场景，目的是确定导致过去100年LOD变化的力量的性质。