自适应网格加密对Ia型超新星点火前对流的高分辨率模拟
High-Resolution Simulations of Convection Preceding Ignition in Type Ia Supernovae Using Adaptive Mesh Refinement
摘要：
我们延长我们以前的三维，全明星模拟的最后几个小时的对流在Ia型超新星点火前，以更高的分辨率使用自适应网格细化能力，我们的低马赫数代码，MAESTRO。我们报告的统计数据的点火的第一个火焰在一个有效的4.34公里的分辨率，和一般的流场特性在一个有效的2.17公里的分辨率。我们发现偏离中心点火是可能的，半径为50公里最有利，可能的范围为40至75公里。这是一致的，与我们以前的粗（8.68公里分辨率）模拟，这意味着我们已经取得了足够的分辨率，在我们可能的点火半径的确定。点火前最后几个热点的动态表明，不太可能出现多次点火的情况。随着分辨率的提高，我们可以更清楚地看到在对流区的一般流动模式，其特征是一个强大的外向羽流与低速回流。我们表明，对流核心是湍流，具有Kolmogorov谱，并且具有比之前认为的更低的湍流强度和更大的积分长度尺度（分别为16 km s $^{-1}$和200 km的量级），并且我们讨论了第一次火焰的潜在后果。
英文摘要：
We extend our previous three-dimensional, full-star simulations of the final hours of convection preceding ignition in Type Ia supernovae to higher resolution using the adaptive mesh refinement capability of our low Mach number code, MAESTRO. We report the statistics of the ignition of the first flame at an effective 4.34 km resolution, and general flow field properties at an effective 2.17 km resolution. We find that off-center ignition is likely, with radius of 50 km most favored and a likely range of 40 to 75 km. This is consistent with our previous coarser (8.68 km resolution) simulations, implying that we have achieved sufficient resolution in our determination of likely ignition radii. The dynamics of the last few hot spots preceding ignition suggest that a multiple ignition scenario is not likely. With improved resolution, we can more clearly see the general flow pattern in the convective region, characterized by a strong outward plume with a lower speed recirculation. We show that the convective core is turbulent with a Kolmogorov spectrum and has a lower turbulent intensity and larger integral length scale than previously thought (on the order of 16 km s$^{-1}$ and 200 km, respectively), and we discuss the potential consequences for the first flames.
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