星际介质自适应网格模拟的基于场长度的精化准则
A Field-length based refinement criterion for adaptive mesh simulations of the interstellar medium
摘要：
多相星际介质的充分建模需要光学薄辐射冷却，包括固有的热不稳定性。发生的冷凝和蒸发界面的大小由所谓的场长度决定，场长度给出了不稳定性被热传导显著阻尼的尺寸。我们的目的是研究的相关性的传导尺度效应的数值模拟中的一个介质和检查的适用性，传统的和替代的自适应网格技术。ISM中的热传导的低物理值定义了多尺度问题，因此促进了自适应网格的使用。在这里，我们介绍了一个新的细化策略，适用于场条件的Koyama和犬冢作为细化标准。所描述的方法是非常相似的Jeans标准的引力不稳定性Truelove和有效地允许跟踪不稳定的气体位于热界面。我们目前的测试计算，证明了更高的精度，新提出的细化标准相比，细化的基础上的局部密度梯度。除了它的有用性作为一个细化触发器，我们没有找到证据支持的字段标准作为数值稳定性的先决条件。
英文摘要：
Adequate modelling of the multiphase interstellar medium requires optically thin radiative cooling, comprising an inherent thermal instability. The size of the occurring condensation and evaporation interfaces is determined by the so-called Field-length, which gives the dimension at which the instability is significantly damped by thermal conduction. Our aim is to study the relevance of conduction scale effects in the numerical modelling of a bistable medium and check the applicability of conventional and alternative adaptive mesh techniques. The low physical value of the thermal conduction within the ISM defines a multiscale problem, hence promoting the use of adaptive meshes. We here introduce a new refinement strategy that applies the Field condition by Koyama & Inutsuka as a refinement criterion. The described method is very similar to the Jeans criterion for gravitational instability by Truelove and efficiently allows to trace the unstable gas situated at the thermal interfaces. We present test computations that demonstrate the greater accuracy of the newly proposed refinement criterion in comparison to refinement based on the local density gradient. Apart from its usefulness as a refinement trigger, we do not find evidence in favour of the Field criterion as a prerequisite for numerical stability.
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