Nonlinear hydrodynamics of cosmological sheets. 1: Numerical techniques and tests
Nonlinear hydrodynamics of cosmological sheets. 1: Numerical techniques and tests
复制标题
宇宙片的非线性流体动力学。
DOI：
10.1086/174335
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发表时间：
1994
期刊：
影响因子：
--
通讯作者：
M. Norman
中科院分区：
文献类型：
--
作者：
W. Y. Anninos;M. Norman
我们介绍了用于构造和验证计算机程序的数值技术和试验，该程序用于研究宇宙中大型薄片结构的多维非线性流体动力学，特别是在各种不稳定情况下此类结构的碎裂。该程序由两个程序组成，流体力学程序ZEUS-2D和颗粒网格程序。Zeus-2D程序使用显式欧拉有限差分技术求解二维流体动力学方程，并进行了修改，纳入了宇宙的膨胀和由于康普顿散射、韧致辐射以及氢和氦冷却而导致的气体冷却。粒子网格编码解决了无碰撞暗物质的运动方程。该代码使用二维笛卡尔坐标，在一个方向上使用非均匀网格，以提供高分辨率的薄板结构。提出了一系列一维和二维线性摄动测试，旨在测试在宇宙膨胀和不膨胀的情况下的水力解算器和泊松解算器。我们还提出了一种辐射冲击波测试，旨在确保该程序正确处理辐射冷却的能力。最后，讨论了一系列一维Zel‘dovich薄饼试验，用于检验暗物质代码和流体解算器在非线性区域的结果，并与Bond等人的结果进行了比较。(1984)和Shapiro&Strike-Marcell(1985)。总体而言，该代码产生了准确和稳定的结果，这为我们进一步研究提供了一个强大的工具。
We present the numerical techniques and tests used to construct and validate a computer code designed to study the multidimensional nonlinear hydrodynamics of large-scale sheet structures in the universe, especially the fragmentation of such structures under various instabilities. This code is composed of two codes, the hydrodynamical code ZEUS-2D and a particle-mesh code. The ZEUS-2D code solves the hydrodynamical equations in two dimensions using explicit Eulerian finite-difference techniques, with modifications made to incorporate the expansion of the universe and the gas cooling due to Compton scattering, bremsstrahlung, and hydrogen and helium cooling. The particle-mesh code solves the equation of motion for the collisionless dark matter. The code uses two-dimensional Cartesian coordinates with a nonuniform grid in one direction to provide high resolution for the sheet structures. A series of one-dimensional and two-dimensional linear perturbation tests are presented which are designed to test the hydro solver and the Poisson solver with and without the expansion of the universe. We also present a radiative shock wave test which is designed to ensure the code's capability to handle radiative cooling properly. And finally a series of one-dimensional Zel'dovich pancake tests used to test the dark matter code and the hydro solver in the nonlinear regime are discussed and compared with the results of Bond et al. (1984) and Shapiro & Struck-Marcell (1985). Overall, the code is shown to produce accurate and stable results, which provide us a powerful tool to further our studies.