High-resolution numerical simulations of unstable colliding stellar winds
High-resolution numerical simulations of unstable colliding stellar winds
复制标题
不稳定碰撞星风的高分辨率数值模拟
DOI：
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发表时间：
2011
期刊：
影响因子：
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通讯作者：
G. Dubus
中科院分区：
文献类型：
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作者：
A. Lamberts;S. Fromang;G. Dubus
我们研究了双星系统中两个超音速风相互作用的流体力学。风的碰撞产生了两个由接触间断隔开的激波。整体结构取决于风的动量通量比η。我们使用自适应网格加密的Ramses程序来研究激波结构，直到η值更小，空间分辨率更高，空间尺度更大。将忽略轨道运动的二维和三维模拟结果与广泛使用的分析结果进行了比较，并讨论了它们的适用性。在绝热极限下，接触不连续处的速度剪切触发了Kelvin-Helmholtz不稳定性。我们量化了由此产生的波动的幅度，并发现即使在适度的初始剪切下，它们也可能是显著的。使用等温状态方程会导致薄壳不稳定性的发展。初始的演化和生长速率使我们能够正式地确定靠近双轴的非线性薄壳不稳定性(NTSI)。在更远的地方出现了一些类似的横向加速度不稳定性。NTSI会产生很大幅度的波动，并主导长期行为。我们指出了适当地遵循这些不稳定性的计算代价。我们的研究提供了一个基本框架，可以与更复杂的模拟结果进行比较，包括附加的物理效应。
We investigate the hydrodynamics of the interaction of two supersonic winds in binary systems. The collision of the winds creates two shocks separated by a contact discontinuity. The overall structure depends on the momentum flux ratio η of the winds. We use the code RAMSES with adaptive mesh refinement to study the shock structure up to smaller values of η, higher spatial resolution and greater spatial scales than have been previously achieved. 2D and 3D simulations, neglecting orbital motion, are compared to widely used analytic results and their applicability is discussed. In the adiabatic limit, velocity shear at the contact discontinuity triggers the Kelvin–Helmholtz instability. We quantify the amplitude of the resulting fluctuations and find that they can be significant even with a modest initial shear. Using an isothermal equation of state leads to the development of thin shell instabilities. The initial evolution and growth rates enables us to formally identify the non-linear thin shell instability (NTSI) close to the binary axis. Some analogue of the transverse acceleration instability is present further away. The NTSI produces large amplitude fluctuations and dominates the longterm behaviour. We point out the computational cost of properly following these instabilities. Our study provides a basic framework to which the results of more complex simulations, including additional physical effects, can be compared.