Self-similar solutions for the dynamical condensation of a radiative gas layer
Self-similar solutions for the dynamical condensation of a radiative gas layer
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DOI：
10.1111/j.1365-2966.2008.13294.x
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发表时间：
2008-06
期刊：
影响因子：
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通讯作者：
K. Iwasaki;T. Tsuribe
中科院分区：
文献类型：
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作者：
K. Iwasaki;T. Tsuribe
在平行平面几何条件下，研究了辐射气体动态凝聚的一种新的自相似解。动态凝聚是由热不稳定性引起的。该解决方案是适用于一般的流动与每单位体积的净冷却速率和时间$\propto\rho^2 T ^\alpha $，其中$\rho $，$T $和$\alpha $是密度，温度和自由参数，分别。给定$\alpha $，我们可以找到一个带有一个参数$\eta $的自相似解族，其中中心密度和压力的演化如下：$\rho（x = 0，t）\propto（t_\mathrm {c}-t）^{-\eta/（2-\alpha）}$和$P（x = 0，t）\propto（t_\mathrm {c}-t）^{（1-\eta）/（1-\alpha）}$，其中$t_\mathrm {c}$是中心密度变为无穷大的时期。对于$\eta\sim 0 $，解描述了等容模式，而对于$\eta\sim 1 $，解描述了等压模式。自相似解存在于两个极限之间的范围内;即，对于$0 $1 $。我们比较所得到的自相似解与一维流体动力学模拟的结果。在收敛流中，数值模拟结果与高密度极限下的自相似解吻合较好。我们的自相似解适用于星际云（HI云和分子云）的热不稳定性的形成。
A new self-similar solution describing the dynamical condensation of a radiative gas is investigated under a plane-parallel geometry. The dynamical condensation is caused by thermal instability. The solution is applicable to generic flow with a net cooling rate per unit volume and time $\propto \rho^2 T^\alpha$, where $\rho$, $T$ and $\alpha$ are density, temperature and a free parameter, respectively. Given $\alpha$, a family of self-similar solutions with one parameter $\eta$ is found in which the central density and pressure evolve as follows: $\rho(x=0,t)\propto (t_\mathrm{c}-t)^{-\eta/(2-\alpha)}$ and $P(x=0,t)\propto (t_\mathrm{c}-t)^{(1-\eta)/(1-\alpha)}$, where $t_\mathrm{c}$ is an epoch when the central density becomes infinite. For $\eta\sim 0$, the solution describes the isochoric mode, whereas for $\eta\sim1$, the solution describes the isobaric mode. The self-similar solutions exist in the range between the two limits; that is, for $0 1$. We compare the obtained self-similar solutions with the results of one-dimensional hydrodynamical simulations. In a converging flow, the results of the numerical simulations agree well with the self-similar solutions in the high-density limit. Our self-similar solutions are applicable to the formation of interstellar clouds (HI cloud and molecular cloud) by thermal instability.