Laboratory Study of Magnetorotational Instability and Hydrodynamic Stability at Large Reynolds Numbers in a Short Couette Flow

长期以来，人们一直认为湍流角动量输运是解释吸积盘吸积的驱动力，原因很简单，因为这些盘具有非常大的雷诺数（Re）。理论和数值研究表明，磁旋转不稳定性（MRI）可以支持剧烈的湍流，因此MRI现在是从类星体到灾难性变量的磁盘吸积的有利机制。然而，MRI需要足够的电离来提供良好的导电性，而冷盘可能无法提供，因此有时会调用流体动力学湍流。本课题是对液态金属中高磁共振成像的实验室实验研究，目的是对高磁共振成像进行演示并研究其非线性行为，研究大磁共振下流体动力流动的稳定性，并将实验室结果与模拟的天体物理盘进行定量比较。这些比较将有助于验证适用于天体物理系统，特别是原恒星盘中电阻性MRI非线性饱和的理论工具。成功需要实验物理学家、计算流体动力学家和理论天体物理学家的共同努力，他们有很多东西需要相互学习。由于实验天体物理学的领域仍然很小，因此对学生的培训将特别有价值。

AST-0607472GoodmanIt has long been assumed that turbulent angular momentum transport is a driving force explaining why accretion disks accrete, simply because such disks have very large Reynolds numbers (Re). Theoretical and numerical studies have shown that magneto-rotational instabilities (MRI) can support vigorous turbulence, so that MRI is now the favored mechanism for accretion in disks ranging from quasars to cataclysmic variables. However, MRI requires sufficient ionization to provide good electrical conductivity, which cool disks may not provide, so hydrodynamic turbulence is sometimes invoked. This project is an experimental laboratory study of high-Re MRI in liquid metal, to demonstrate MRI and study its nonlinear behavior, to investigate the stability of hydrodynamic flows at large Re, and to compare the laboratory results quantitatively with simulated astrophysical disks. These comparisons will help to validate theoretical tools applicable to nonlinear saturation of resistive MRI in astrophysical systems, especially proto-stellar disks.Success will require the combined efforts of experimental physicists, computational fluid-dynamicists, and theoretical astrophysicists, who have much to learn from one another. Student training will be particularly valuable, since the field of experimental astrophysics is still rather small.