Modelling turbulent effects of stellar feedback in cosmological simulations

In order to study the influence of turbulence on star formation, stellar feedback, and the mixing of metals into the intergalactic medium (IGM) in numerical experiments, we implemented a model for star formation and stellar feedback and employ it in cosmological large eddy simulations using a subgrid scale (SGS) turbulence model. We find that star formation decreases and the efficiency of feedback increases if only SGS terms related to the turbulent cascade and dissipation are incorporated into the equations of gas dynamics. This in turn leads to stronger outflows. Additional injection of turbulent energy by feedback, however, does not affect diagnostics like star formation rates (SFRs) or outflow radii significantly. We also show that turbulent diffusion of metal species does not necessarily lead to a higher enrichment in the IGM, while turbulent diffusion of internal energy results in a global SFR and stacked halo profiles that are almost indistinguishable from the case with no SGS model at all.