Anelastic and Compressible Simulations of Stellar Oxygen Burning
Anelastic and Compressible Simulations of Stellar Oxygen Burning
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DOI：
10.1086/519372
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发表时间：
2006-11
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影响因子：
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通讯作者：
C. Meakin;D. Arnett
中科院分区：
文献类型：
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作者：
C. Meakin;D. Arnett
在本文中，我们比较了完全可压缩（Meakin & Arnett 2006，2007）和滞弹性（Kuhlen et al. 2003）模拟恒星氧壳燃烧。结果表明，两种模型在速度尺度（vc ~ 107 cm s-1）和热力学涨落幅度（例如，ρ′/<$ρ <$~ 2 × 10-3）。大的波动（~11%）出现在可压缩模型，局部对流边界，是由于内波激发稳定层。在几个百分比的水平上的波动也存在于可压缩模型中，由于对流边界处正在进行的卷吸事件的成分不均匀性。在滞弹性模拟中不存在类似的波动（振幅大于~1%），因为它们是由该模型中不包括的物理学引起的。假设边界处内波引起的压力波动p与对流运动的冲压压力ρv相平衡，我们推导出对流边界处预期密度波动幅度的解析估计。预测的振幅与模拟数据吻合较好。在对流区的滞弹性和可压缩的解决方案之间的良好协议和协议之间的稳定层动力学和非径向波动方程的解析解表明，可压缩流体动力学技术使用的模拟恒星对流模型是强大的，即使在低马赫数发现，M ~ 0.01。
In this paper we compare fully compressible (Meakin & Arnett 2006, 2007 ) and anelastic (Kuhlen et al. 2003) simulations of stellar oxygen shell burning. It is found that the two models are in agreement in terms of the velocity scale (vc ~ 107 cm s-1) and thermodynamic fluctuation amplitudes (e.g., ρ′/⟨ρ⟩ ~ 2 × 10-3) in the convective flow. Large fluctuations (~11%) arise in the compressible model, localized to the convective boundaries, and are due to internal waves excited in stable layers. Fluctuations on the several percent level are also present in the compressible model due to composition inhomogeneities from ongoing entrainment events at the convective boundaries. Comparable fluctuations (with amplitudes greater than ~1%) are absent in the anelastic simulation, because they are due to physics not included in that model. We derive an analytic estimate for the expected density fluctuation amplitudes at convective boundaries by assuming that the pressure fluctuations due to internal waves at the boundary, p, balance the ram pressure of the convective motions, ρv. The predicted amplitudes agree well with the simulation data. The good agreement between the anelastic and the compressible solution within the convection zone and the agreement between the stable layer dynamics and analytic solutions to the nonradial wave equation indicate that the compressible hydrodynamic techniques used are robust for the simulated stellar convection model, even at the low Mach numbers found, M ~ 0.01.