Kinetic simulations of thermal escape from a single component atmosphere
Kinetic simulations of thermal escape from a single component atmosphere
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单组分大气热逃逸的动力学模拟
DOI：
10.1063/1.3592253
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发表时间：
2011
影响因子：
4.6
通讯作者：
Robert E. Johnson
中科院分区：
文献类型：
--
作者：
A. Volkov;O. Tucker;Justin T. Erwin;Robert E. Johnson
本文用直接模拟蒙特卡罗方法研究了单原子气体在重力场中从球形源出发的一维稳态膨胀。分子间的碰撞采用硬球模型描述，气体分子离开源表面的分布假定为麦克斯韦分布，模拟区域内没有热量直接沉积。分析了源Jeans参数λ0（分子的引力能与热能之比）和Knudsen数Kn 0（平均自由程与源半径之比）分别在0 ~ 15和0.0001 ~ ∞范围内时的流场结构和逃逸率（分子逃逸的数通量）。在无碰撞区域，分析了λ0=0-100的流动，得到了气体参数渐近值的解析方程，发现这些气体参数是λ0的非单调函数。对于碰撞流，模拟预测过渡的大气损失的性质，从逃逸的M…
The one-dimensional steady-state expansion of a monatomic gas from a spherical source in a gravity field is studied by the direct simulation Monte Carlo method. Collisions between molecules are described by the hard sphere model, the distribution of gas molecules leaving the source surface is assumed to be Maxwellian, and no heat is directly deposited in the simulation region. The flow structure and the escape rate (number flux of molecules escaping the atmosphere) are analyzed for the source Jeans parameter λ0 (ratio of the gravitational energy to thermal energy of the molecules) and Knudsen number Kn0 (ratio of the mean free path to the source radius) ranging from 0 to 15 and from 0.0001 to ∞, respectively. In the collisionless regime, flows are analyzed for λ0=0-100 and analytical equations are obtained for asymptotic values of gas parameters that are found to be non-monotonic functions of λ0. For collisional flows, simulations predict the transition in the nature of atmospheric loss from escape on a m...