Enzo+Moray：辐射流体动力学自适应网格细化模拟与自适应光线跟踪
Enzo+Moray: Radiation Hydrodynamics Adaptive Mesh Refinement Simulations with Adaptive Ray Tracing
摘要：
我们描述了一个光子守恒的辐射转移算法，使用空间自适应射线追踪计划，并将其并行实施到自适应网格细化（AMR）宇宙流体动力学代码，恩佐。通过耦合求解器与能量方程和非平衡化学网络，我们的辐射流体力学框架可以用来研究广泛的天体物理问题，如恒星和黑洞（BH）的反馈。大的时间步长和差的采样可能会导致不准确，因此我们设计了一个自适应的时间步长方案和多源光薄辐射场的快速近似。我们测试的方法与几个辐射转移和辐射流体力学测试，在伊利耶夫等人。（2006年，2009年）。我们进一步测试我们的方法与更多的动态情况下，例如，传播的电离前通过瑞利-泰勒不稳定性，随时间变化的光度，和准直辐射。该测试套件还包括一个扩展的H II区域的磁化介质，利用新实施的磁流体力学模块恩佐。该方法与点源数量和网格单元数量呈线性关系。我们的实现是可扩展到512处理器上的分布式存储器机器，可以包括辐射压力和二次电离从X射线辐射。它包含在恩佐的最新公开版本中。
英文摘要：
We describe a photon-conserving radiative transfer algorithm, using a spatially-adaptive ray tracing scheme, and its parallel implementation into the adaptive mesh refinement (AMR) cosmological hydrodynamics code, Enzo. By coupling the solver with the energy equation and non-equilibrium chemistry network, our radiation hydrodynamics framework can be utilised to study a broad range of astrophysical problems, such as stellar and black hole (BH) feedback. Inaccuracies can arise from large timesteps and poor sampling, therefore we devised an adaptive time-stepping scheme and a fast approximation of the optically-thin radiation field with multiple sources. We test the method with several radiative transfer and radiation hydrodynamics tests that are given in Iliev et al. (2006, 2009). We further test our method with more dynamical situations, for example, the propagation of an ionisation front through a Rayleigh-Taylor instability, time-varying luminosities, and collimated radiation. The test suite also includes an expanding H II region in a magnetised medium, utilising the newly implemented magnetohydrodynamics module in Enzo. This method linearly scales with the number of point sources and number of grid cells. Our implementation is scalable to 512 processors on distributed memory machines and can include radiation pressure and secondary ionisations from X-ray radiation. It is included in the newest public release of Enzo.
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