Magnetohydrodynamic Simulations of Molecular Cloud Formation

Kritsuk博士和他的团队用高分辨率的数值模拟研究了分子云中磁化湍流和星星形成的动力学。计算是用恩佐代码完成的，恩佐代码是一种自适应网格细化和基于网格的混合代码（流体力学和N体），旨在模拟天体物理和宇宙学结构的形成。自洽计算模型的影响，如重力，微分旋转，辐射传输的可压缩磁流体动力学（MHD）湍流的自组织在多相星际介质。这里的模型结合了更复杂的物理，更高的动态范围的分辨率尺度，并采用改进的数值方法。特别地，模型包括多相MHD湍流的标度及其随湍流磁化的变化。分子云形成的MHD模型的动态范围的模拟利用千万亿次计算设备，并试图解决在多相星际介质中的超声速磁化湍流的惯性范围。这将测试竞争的星星形成模型和唯象理论时，模拟比较观察。更广泛地说，为了理解高能粒子的加速和传播，以及各种天体物理系统中动量和能量的传输，也需要更好地理解湍流。作为该项目的一部分，一名研究生将接受培训，学习超音速MHD流动建模的数值方法，大规模并行计算机模拟，以及磁化多相湍流的统计分析和可视化方法。

Dr. Kritsuk and his team study dynamics of magnetized turbulence and star formation in molecular clouds with numerical high-resolution simulations. The computations are done with the Enzo code, an Adaptive Mesh Refinement and grid-based hybrid code (hydrodymamics and N-body), which is designed to do simulations of astrophysical and cosmological structure formation. The self-consistent computations model effects such as gravity, differential rotation, and radiative transfer on the self-organization in compressible magneto-hydrodynamic (MHD) turbulence in the multiphase interstellar medium. The models here incorporate more complex physics, a higher dynamic range of resolved scales, and employ improved numerical methods. In particular, the modeling includes the scaling of multiphase MHD turbulence and its change with the turbulence magnetization. The simulations for the dynamic range of MHD models for molecular cloud formation utilize petascale computational facilities and attempt to resolve the inertial range of supersonic magnetized turbulence in the multiphase interstellar medium. This will test competing star formation models and phenomenological theories when the simulations are compared to observations. More broadly, a better understanding of turbulence is also needed for understanding the acceleration and propagation of energetic particles, transport of momentum and energy in various astrophysical systems. As part of this project, one graduate student will be trained in the development of numerical methods for modeling supersonic MHD flows, in large-scale parallel computer simulations, and in methods for statistical analysis and visualization of magnetized multiphase turbulent flows.