Scaling with the Stars: The emergence of marginal stability in low Prandtl number turbulence

Abstract: To improve models of the structure and evolution of stellar and planetary interiors, it is important to quantify transport by strongly stratified turbulence in low Prandtl number fluids. Recent numerical studies have shown evidence for scale-separated dynamics in strongly anisotropic flows. Motivated by these results, in the first part of this report we perform a multiscale analysis of the governing equations and identify regimes of behaviour. In the second part, we apply algorithms for solving slow-fast quasilinear systems to our reduced-order systems for low Prandtl number fluids and demonstrate their approach to and maintenance of marginal stability. This is a Fellow's Report for the 2022 Program of the Geophysical Fluid Dynamics Summer School.