The interplay of stellar luminosity variations and dust hydrodynamics in Asymptotic Giant Branch (AGB) stars and the consequences for dust survival and mass loss remain elusive. In this work, we broadly investigate the role of dust and radiation hydrodynamics in forming dust and gas structures, heterogeneous clumps observable in AGB remnants and planetary nebulae (PNe). Of interest in this study are the spatial perturbations driven by instabilities in the space that the mass travels through. These spatial perturbations in the dust and gas field may be responsible for forming larger clumps, such as cometary knots, seen in the PNe phase. Previous studies have considered similar physics in dust-driven winds at shorter lengths and time scales, using either 1D simulations or 2D simulations with a single mixed particle–gas fluid. Here we present an Eulerian–Lagrangian method for studying this problem at larger length and time scales. Simulations are performed in 2D, solving the Euler equations with source terms resulting from the particle phase, represented by free Lagrangian points. Radiation coupling was implemented for the particle phase, modeling radiation heating and acceleration of the particles and subsequent coupling to the gas phase through non-continuum heat and momentum transfer models. Spatial perturbations of the dust and radiation fields were found to drive the formation of small dust mass clumps that survive to late times, though these remain below the size of those observed in many PNe.

渐近巨分支（AGB）恒星中恒星光度变化和尘埃流体动力学的相互作用以及尘埃存活和质量损失的后果仍然难以捉摸。在这项工作中，我们广泛研究了尘埃和辐射流体动力学在形成尘埃和气体结构、AGB 残余物和行星状星云 (PNe) 中可观察到的异质团块中的作用。这项研究感兴趣的是由质量穿过的空间的不稳定性引起的空间扰动。尘埃和气体场中的这些空间扰动可能是形成更大团块的原因，例如在 PNe 阶段看到的彗星结。先前的研究已经考虑了较短长度和时间尺度的尘埃驱动风中的类似物理现象，使用单一混合颗粒气体流体的一维模拟或二维模拟。在这里，我们提出了一种欧拉-拉格朗日方法，用于在更大的长度和时间尺度上研究这个问题。模拟以二维方式进行，使用由自由拉格朗日点表示的粒子相产生的源项求解欧拉方程。对粒子相实施辐射耦合，对粒子的辐射加热和加速进行建模，并随后通过非连续热和动量传递模型耦合到气相。人们发现，尘埃和辐射场的空间扰动会促使小尘埃团块的形成，这些尘埃团块会存活到晚期，尽管这些尘埃团块的大小仍然低于在许多PNe中观察到的大小。