模拟恒星和盘形成过程中的尘埃凝聚、动力学阻力和湍流混合
Modelling dust coagulation, dynamical drag and turbulent mixing during star and disc formation
AI总结：
本文提出了一种结合隐式积分方法和SPH模拟的模型，用于研究恒星形成早期阶段和原行星盘中尘埃颗粒的凝聚、混合与迁移过程，通过湍流扩散提高尘埃颗粒生长效率。
摘要：
行星形成过程中，围绕年轻恒星的盘中，微米级的尘埃颗粒会凝聚成更大的颗粒，这些颗粒可能通过湍流混合并迁移通过盘。本文描述了我们如何将一种用于建模尘埃颗粒凝聚的方法与MULTIGRAIN算法结合，该算法用于建模受强气体阻力影响的尘埃颗粒动力学演化。我们使用一种 recently-developed 的隐式积分方法来解决气体阻力对尘埃颗粒动态演化的影响，并引入了一种新的隐式方法来建模由于未解析的流体动力学湍流导致的尘埃扩散。由此产生的 smoothed particle hydrodynamics (SPH) 代码使我们能够首次通过三维流体动力学模拟来建模恒星形成早期阶段和年轻原行星盘的尘埃颗粒生长、混合和迁移，以及盘的形成、生长和演化。在此过程中，我们发现，在盘中包括湍流尘埃扩散能够显著提高尘埃颗粒生长的速率，因为湍流扩散为生长最大尘埃颗粒的区域提供了小和中等大小的尘埃颗粒来源。
英文摘要：
Planet formation in the discs around young stars involves the coagulation of sub-micron sized dust grains into much larger grains that may be mixed by turbulence and migrate through the disc. In this paper, we describe how we have combined a method for modelling the coagulation of a population of dust grains with the MULTIGRAIN algorithm for modelling the dynamical evolution of a population of dust grains that are subject to strong gas drag. We solve the dynamical evolution of the dust grains due to gas drag using a recently-developed implicit integration method, and we introduce a new implicit method to model the diffusion of the dust due to unresolved hydrodynamic turbulence. The resulting smoothed particle hydrodynamics (SPH) code allows us, for the first time, to model the growth, mixing and migration of dust grain populations during the early stages of star formation and the formation, growth and evolution of a young protoplanetary disc using three-dimensional hydrodynamical simulations. In doing so, we find that including turbulent dust diffusion within the disc provides a substantial enhancement of the rate of dust grain growth due to the fact that the turbulent diffusion provides a source of small and intermediate dust grains to the regions in which the largest dust grains are growing.
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