Abstract

The question of how dust grains are able to grow past the three growth barriers has been central to the study of planet formation over the past decades. Several ideas have been analysed, from gravitational instabilities of the dust within the protoplanetary disc, to dust clumping due to dust-gas hydrodynamic instabilities. In this talk I discuss the streaming instability in the context of planet formation, and the role vortices may play in gathering dust in protoplanetary discs. The streaming instability appears strongly damped by dust size distributions, leading to a requirement for strong previous dust enrichment. Vortices may be able to provide such an enrichment, but dust drag instabilities may also be the culprit when it comes to breaking up vortex cores. Study of 2D dusty vortices shows weak dust-drag instability which breaks up vortex cores, but this instability is not fast enough to prevent strong dust enrichment in vortex cores.