标题： 流体不稳定性物理机制 显示英文标题

标题： The physical mechanism of the streaming instability

摘要： 行星形成理论的主要障碍是米级障碍。 克服这一障碍最有希望的方法是通过流不稳定（SI）。 不幸的是，导致这种不稳定性出现的机制仍然神秘。 最近的研究表明，SI是一种涉及惯性波的共振拖曳不稳定性（RDI）。 我们在此基础上，阐明了SI发展的物理图景，并通过清晰的数学方法加强这一图景。 与所有RDI一样，SI建立在一个反馈回路之上：在“前向作用”中，惯性波将尘埃集中成团；在“反向反应”中，这些漂移的尘埃团激发一个惯性波。 每个过程分为两种机制，一种是快速的，另一种是缓慢的。 在共振时，每个前向机制可以与一个反向机制耦合以形成一个反馈回路。 不幸的是，快-快回路是稳定的，因此SI使用快-慢和慢-快回路。 尽管有这一层复杂性，我们希望我们的解释能够帮助理解SI是如何工作的，在什么条件下它可以增长，它如何表现出来，以及它如何达到饱和。 显示英文摘要

摘要： The main hurdle of planet formation theory is the metre-scale barrier. One of the most promising ways to overcome it is via the streaming instability (SI). Unfortunately, the mechanism responsible for the onset of this instability remains mysterious. It has recently been shown that the SI is a Resonant Drag Instability (RDI) involving inertial waves. We build on this insight and clarify the physical picture of how the SI develops, while bolstering this picture with transparent mathematics. Like all RDIs, the SI is built on a feedback loop: in the `forward action', an inertial wave concentrates dust into clumps; in the `backward reaction', those drifting dust clumps excite an inertial wave. Each process breaks into two mechanisms, a fast one and a slow one. At resonance, each forward mechanism can couple with a backward mechanism to close a feedback loop. Unfortunately, the fast-fast loop is stable, so the SI uses the fast-slow and slow-fast loops. Despite this last layer of complexity, we hope that our explanation will help understand how the SI works, in which conditions it can grow, how it manifests itself, and how it saturates.