Speaker
Description
We investigate a dust-driven vertical shear instability (DVSI) in a radially local, vertically stratified isothermal shearing box. Unlike the classical vertical shear instability, which relies on baroclinicity from global thermodynamic gradients (radial temperature gradients with finite cooling), DVSI is triggered by dust backreaction that generates axisymmetric vertical shear in an otherwise barotropic setup. We construct vertically stratified two-fluid equilibria including dust diffusion and use these profiles to initialise 2D hydrodynamical simulations with FARGO3D. To cleanly separate DVSI from drag-driven instabilities, we primarily adopt a “dust-analogue” approach in which dust backreaction is imposed as a prescribed height-dependent acceleration on the gas, with no dynamical dust feedback. DVSI grows fastest in off-midplane layers where the vertical shear is strongest, exciting predominantly radially short, vertically extended modes (large kx/kz). During the linear phase, the instability produces characteristic banded perturbations in the azimuthal and vertical velocities. In the non-linear regime, DVSI saturates via a Kelvin–Helmholtz-like parasitic instability that disrupts coherent vertical-shear modes into smaller-scale eddies. The resulting balance between mode growth and parasitic breakup sustains anisotropic turbulence and persistent vertical stirring. Our results demonstrate that dust-induced vertical shear alone can drive vertical mixing in an isothermal local model, without invoking global thermal gradients.
| Talk category | NOVA Network 2 |
|---|---|
| PhD relevance | 3rd |
