Simulations and theory of mechanically driven, turbulent dynamos in spherical geometry

球面几何中机械驱动的湍流发电机的模拟和理论

• 批准号: 132689836
• 负责人: Professor Dr. Frank Jenko
• 金额: --
• 依托单位: Institut für Astrophysik und Geophysik
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2009
• 资助国家: 德国
• 起止时间: 2008-12-31 至 2014-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/132689836?language=en
• 关键词: Simulations; theory; mechanically; driven; turbulent

The Earth and most of the planets in the solar system, the Sun and other stars, galaxies and galaxy clusters all have magnetic fields which cannot be explained by permanent magnetization. It is generally accepted that these fields are produced by the dynamo effect. In the last few years, remarkable progress has been achieved in validating certain key theoretical concepts via laboratory experiments (e.g., at Riga, Karlsruhe, Maryland, Madison, and Cadarache). Due to the use of liquid sodium, these recent (and ongoing) experiments inevitably involve highly turbulent flows which are expected to play a critical role in the dynamo transition. In order to better understand the nature, role, and control of turbulent flows in mechanically driven, bounded dynamos, we plan to perform numerical simulations with existing, parallel, nonlinear MHD codes, complemented by theoretical investigations. Mainly two type of flows will be studied. Both are in spherical geometry, and both are related to current experiments. One is the flow of two counter-rotating propellers in a stationary spherical vessel, the other is a rotating sphere within a second, concentric, rotating spherical container (spherical Couette flow). One of the central questions to be addressed is the dependence of the critical magnetic Reynolds number on the fluid Reynolds number. The common proposal has the advantage that some fundamental problems with possibly similar solutions can be approached cooperatively.

太阳系，太阳和其他恒星，星系和星系簇中的地球和大多数行星都有磁场，这些磁场无法通过永久性磁化来解释。人们普遍认为，这些磁场是由发电机效应产生的。在过去的几年中，通过实验室实验验证某些关键理论概念（例如，在Riga，Karlsruhe，Maryland，Maryland，Madison和Cadarache）方面取得了显着进步。由于使用液体钠，这些最近（和正在进行的）实验不可避免地涉及高度湍流，预计在发电机过渡中起关键作用。为了更好地了解机械驱动的，有界的发电机中湍流的性质，作用和控制，我们计划使用理论研究补充的现有，平行的非线性MHD代码进行数值模拟。将研究两种类型的流。两者都处于球形几何形状中，并且都与当前的实验有关。一个是在固定球形容器中的两个反向旋转螺旋桨的流动，另一个是旋转的球体，旋转的球体，同心旋转的球形容器（球形cOETTE COUETTE流动）。要解决的中心问题之一是临界磁性雷诺数对流体雷诺数的依赖性。共同的提议的优势是，可以合作解决一些可能具有类似解决方案的基本问题。