Abstract

Planet accretion models predict that terrestrial planets form by successive collisions in a disk of orbiting objects. During the late, most energetic collisions, shock waves melt the colliding embryos, which then behave as fluids. Existing simulations of these collisions reproduce the large-scale flow, but cannot resolve the smallest scales. The small-scale processes are however crucial to predict the mixing between the colliding embryos and the composition of the post-impact planet.

In contrast, laboratory experiments fully resolve small-scale turbulence and mixing. I will present experiments on the impact of a liquid volume with a liquid layer in a regime relevant to planetary accretion events. From these, we obtain scaling laws for mixing of the impactor as a function of impact velocity, impactor size and density difference. I will discuss implications for chemical equilibration during planetary impacts.