The problem

• Dust grains should settle. What keeps them up?

Possible solution

• Mixing due to macroscopic flows. But which?

RHD simulations with CO⁵BOLD

• General: 2D Cartesian box, 400x360 grid points, constant gravity
• Hydrodynamics: 1D approximate Riemann solver
• Radiation transport: non-local, non-grey 5-bin opacity scheme (PHOENIX data)
• Monomers and dust: Additional densities, Forsterite (Mg₂SiO₄), 2-bin or multi-bin

Aim

• Investigation of basic transport mechanisms for dust and gas
• Derivation of 1D mixing description to be included in PHOENIX