Dynamics and transport of magnetorotational instabilities in Taylor--Couette flows

泰勒-库埃特流中磁旋转不稳定性的动力学和输运

基本信息

批准号：
230979418
负责人：
Professor Dr. Marc Avila Canellas
金额：
--
依托单位：
Zentrum für angewandte Raumfahrttechnologie und Mikrogravitation (ZARM)
依托单位国家：
德国
项目类别：
Research Grants
财政年份：
2013
资助国家：
德国
起止时间：
2012-12-31 至 2017-12-31
项目状态：
已结题

来源：
https://gepris.dfg.de/gepris/projekt/230979418?language=en
关键词：
Dynamics transport magnetorotational instabilities Taylor

项目摘要

Turbulent transport of gas is a necessary physical process to explain the rates at which matter accretes and solar systems form in astrophysical disks. However, angular momentum increases radially in such disks and hence gas motion is expected to be laminar according to the Rayleigh criterion for rotating fluids. The solution to this riddle is provided by the magnetorotational instability (MRI), which operates in disks provided that the gas is ionized. In the last two decades there has been a great deal of numerical studies studying the properties of the MRI. Simulations are usually performed using the shearing sheet approximation, which is a local model of an accretion disk. Recently, there has been considerable interest in obtaining the MRI in laboratory experiments. The canonical experiment for the MRI is the swirling flow of a liquid metal between two concentric and independently rotating cylinders with an imposed axial magnetic field. Linear stability studies of this problem have been carried out, and shown to be in reasonable agreement with experiment for helical magnetic fields. However, little is known of the nonlinear saturation, bifurcation scenario, transition to turbulence and transport properties of the MRI, which is crucial for accretion in disks.The main goal of this project is to provide a characterization of magnetorotational instabilities in flows between corotating cylinders in the nonlinear regime. The various flavors of the MRI, corresponding to different magnetic field configurations, will be contrasted with one another, and transport scaling will be computed and used to infer properties in the astrophysical context. The results will be extensively compared with properties of the same instability in the shearing sheet approximation, in which the imposed radially periodic boundary conditions are thought to play a key role in the nonlinear saturation and properties of the turbulent flow. The project will provide a wealth of data for benchmarking and especially for comparison with laboratory experiments that have already been performed or are either under way or planned.

气体的湍流运输是一个必要的物理过程，以解释天体物理磁盘中物质增生和太阳系形成的速率。然而，根据旋转流体的瑞利标准，该磁盘中的角动量在此类磁盘中径向增加，因此气体运动有望为层流。如果气体被离子化，则在磁盘中运行的磁化不稳定性（MRI）提供了解决这个谜的解决方案。在过去的二十年中，研究了MRI的性质很多数字研究。通常使用剪切片近似进行模拟，该剪切板是积聚磁盘的局部模型。最近，在实验室实验中获得MRI引起了极大的兴趣。 MRI的规范实验是带有轴向磁场的两个同心和独立旋转的圆柱体之间液体金属的旋流。已经对此问题进行了线性稳定性研究，并证明与螺旋磁场的实验合理一致。然而，对非线性饱和度，分叉场景，向MRI的湍流和运输特性的过渡鲜为人知，这对于在磁盘中的积聚至关重要。该项目的主要目的是提供非线性旋转器之间的流动cylinders磁性不稳定的表征。对应于不同磁场构型的MRI的各种口味将彼此对比，并将计算传输缩放率，并用于在天体物理环境中推断特性。将结果与剪切板近似中相同不稳定性的性质进行比较，在剪切片近似中，施加的径向周期性边界条件被认为在非线性饱和和湍流的特性中起关键作用。该项目将提供大量的基准测试数据，尤其是与已经进行或正在进行的实验实验进行比较的数据。