Min-Kai Lin (ASIAA)
In the standard picture of planet formation, dust grains first settle into the midplane of protoplanetary discs, forming a dense particle layer, before undergoing planetesimal formation. However, this picture assumes a laminar disc. In recent years, several hydrodynamic sources of turbulence in protoplanetary discs have been identified. This includes the vertical shear instability (VSI), relevant to the irradiated parts of protoplanetary discs. We perform high resolution dusty-gas simulations to study how particle dynamics is affected by VSI-turbulence. We find small particles at Solar metallicity cannot settle against the VSI, and remain well mixed with the gas throughout the disc's vertical extent. However, boosting the metallicity helps the particles to settle due dust-induced buoyancy forces, itself arising from the back-reaction of dust drag on the gas. Our results restrict the particle sizes and metallicities relevant for planetesimal formation in order for dust to settling against the VSI.