标题： 多维磁流体动力学模拟中的过渡区自适应传导（TRAC） 显示英文标题

标题： Transition region adaptive conduction (TRAC) in multidimensional magnetohydrodynamic simulations

摘要： 在太阳物理学中，现代模拟面临的一个严重数值挑战是正确表示百万度高温日冕与约10000 K的较冷等离子体之间的过渡区域（例如，上色球层或日珥）。 在以前的一维流体动力学模拟中，过渡区域自适应导热（TRAC）方法已被证明能够更好地捕捉与质量蒸发和能量交换相关的方面。 我们的目标是将这种方法扩展到完全多维磁流体动力学（MHD）设置中，这在太阳大气中的任何实际应用中都是必需的。 由于现代MHD模拟工具能够高效利用并行超级计算机并处理自动网格细化，我们设计了适用于任意维度的块网格自适应MHD模拟策略。 我们提出了两种不同的策略，并用我们的开源MPI-AMRVAC代码展示了它们的工作情况。 我们在基于蒸发-凝结情景的二维日珥形成问题上对这两种策略进行了基准测试，其中色球等离子体通过过渡区域蒸发，然后被收集并最终在日冕中凝结。 引入并比较了基于场线的TRACL方法和基于块的TRACB方法，在块网格自适应的二维MHD模拟中进行比较。 两种方法得出的结果相似，并被证明可以令人满意地纠正因过渡区域空间分辨率不足而导致的色球蒸发低估问题。 由于在多维MHD设置中完全解析过渡区域几乎是不可能的，因此在涉及过渡区域物理的任何二维或三维模拟中都需要使用TRACB或TRACL方法。 显示英文摘要

摘要： In solar physics, a severe numerical challenge for modern simulations is properly representing a transition region between the million-degree hot corona and a much cooler plasma of about 10000 K (e.g., the upper chromosphere or a prominence). In previous 1D hydrodynamic simulations, the transition region adaptive conduction (TRAC) method has been proven to capture aspects better that are related to mass evaporation and energy exchange. We aim to extend this method to fully multidimensional magnetohydrodynamic (MHD) settings, as required for any realistic application in the solar atmosphere. Because modern MHD simulation tools efficiently exploit parallel supercomputers and can handle automated grid refinement, we design strategies for any-dimensional block grid-adaptive MHD simulations. We propose two different strategies and demonstrate their working with our open-source MPI-AMRVAC code. We benchmark both strategies on 2D prominence formation based on the evaporation--condensation scenario, where chromospheric plasma is evaporated through the transition region and then is collected and ultimately condenses in the corona. A field-line-based TRACL method and a block-based TRACB method are introduced and compared in block grid-adaptive 2D MHD simulations. Both methods yield similar results and are shown to satisfactorily correct the underestimated chromospheric evaporation, which comes from a poor spatial resolution in the transition region. Because fully resolving the transition region in multidimensional MHD settings is virtually impossible, TRACB or TRACL methods will be needed in any 2D or 3D simulations involving transition region physics.