Analysis of a Multiphase Radiation-Driven Rayleigh-Taylor Instability

The physics of multiphase (particle-gas) Radiation-driven Rayleigh-Taylor Instability (RRTI) are central to understanding various astrophysical phenomena, especially the dust-laden stellar winds of asymptotic giant branch stars. While previous studies have examined the formation of instabilities during the initial stages of dust condensation, none have fully accounted for the multiphase effects, such as velocity slip between the dust and gas, that introduce additional complexity to the instability. When the dust and gas are not fully coupled, particles will detach from the flow field and may be concentrated in clusters. This study delves into the multiphase RRTI, concentrating on the role of high-opacity dust particles and their influence on the instability and its associated hydrodynamic growth. Numerical simulations are performed in the FLASH code and use an added radiation-particle coupling mechanism for this study. We examine the consequences of velocity equilibration rate, arising due to varying particle sizes, and how these different amounts of slip impact the dynamics and evolution of the RRTI. The effect of competing gravitational and radiation accelerations will be discussed and the effect of radiation heating of the gas and resulting gas buoyancy explored. The knowledge obtained from our research can improve astrophysical models and simulation techniques, allowing more precise depictions of the complex dynamics stemming from particle-gas-radiation interactions.