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7/7/2025 4:56:02 PM
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  • Institute of Astronomy and Astrophysics
Hydrodynamical simulations of the vertical shear instability with dynamic dust and cooling rates in protoplanetary disks

2025-02-18 14:40 - 15:40

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Turbulence in protoplanetary disks affects dust evolution and planetesimal formation. The vertical shear instability (VSI) is one of the candidate turbulence-driving mechanisms in the outer part of the disks. Since the VSI requires rapid gas cooling, dust particles in disks can influence and potentially control VSI-driven turbulence. However, VSI-driven turbulence has strong vertical motion, causing vertical diffusion of dust particles. We perform global two-dimensional hydrodynamical simulations of an axisymmetric protoplanetary disk to investigate how the VSI drives turbulence and maintains a balance between dust settling and diffusion. These simulations account for the dynamic interplay between dust distribution, cooling rates, and VSI-driven turbulence. We find that VSI mixing, dust settling, and the local dust cooling reach an equilibrium, forming a thick dust layer with a dimensionless vertical mixing coefficient of approximately $10^{-3}$. The ability of VSI to sustain this equilibrium depends on dust size and dust-to-gas mass ratio. Larger grains or lower mass ratios weaken the turbulence, leading to dust settling. Our results suggest that in VSI-dominated disks, dust grows under turbulence with intensity varying by dust size. Finally, I will talk about the application of the early disk stage and further planet formation.

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