论文标题

聚集云的流体动力学:起草,生存,凝结和消融

Hydrodynamics of Clustered Clouds: Drafting, Survival, Condensation, and Ablation

论文作者

Williams, M. Elliott, Shelton, Robin L.

论文摘要

对于对麦哲伦流(MS)云进行编目的人,他建议MS中存在很大的大规模湍流。在这里,我们进行了一系列的闪光模拟,这些模拟对云彼此产生的流体动力效应进行了建模。模拟套件包括一系列云分离距离和密度。环境条件与周围MS的条件相似,但也与海乳培养基和银河系培养基有关。提出了十个模拟,其中八个模型聚集云和两个模型隔离云。隔离的云被用作与多云模拟进行比较的控件。我们发现,如果云最初彼此接近,那么流体动力的起草有助于尾云捕捉领先的云并混合在一起。我们提出了由于起草而导致的加速度,并发现低密度环境中的较低密度云比其较密集的同类群体更加加速。我们发现,云的聚集也增加了环境材料的凝结并影响寿命。我们使用单个组件方法和多组分分解方法分析云的速度分散。我们发现,第二云的存在会在某些时候增加后云后面的速度分散体。我们发现,我们的模拟中气体运动引起的速度分散体显着少于For等人观察到的实际分散体,这表明热成分必须在MS中占主导地位。

For et al., who catalogued Magellanic Stream (MS) clouds, suggested that there is substantial large-scale turbulence in the MS. Here we follow up with a series of FLASH simulations that model the hydrodynamic effects that clouds have on each other. The suite of simulations includes a range of cloud separation distances and densities. The ambient conditions are similar to those surrounding the MS but also relevant to the circumgalactic medium and intergalactic medium. Ten simulations are presented, eight of which model clustered clouds and two of which model isolated clouds. The isolated clouds are used as controls for comparison with the multicloud simulations. We find that if the clouds are initially near each other, then hydrodynamical drafting helps the trailing cloud to catch the leading cloud and mix together. We present the measured acceleration due to drafting and find that lower-density clouds in lower-density environments experience more acceleration due to drafting than their denser cohorts. We find that the clustering of clouds also increases the condensation of ambient material and affects longevity. We analyze the velocity dispersion of the clouds using a single component method and a multicomponent decomposition method. We find that the presence of a second cloud increases the velocity dispersion behind the trailing cloud at some times. We find that the velocity dispersion due to gas motion in our simulations is significantly less than the actual dispersion observed by For et al., indicating that the thermal component must dominate in the MS.

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