Abstract

Contributed Talk - Splinter Computational

Friday, 13 September 2024, 15:05   (S26)

Multi-fluid methods in galaxy formation simulations

Rainer Weinberger
Leibniz Institute for Astrophysics Potsdam (AIP)

Gas in and around galaxies can be frequently found in a multi-phase state: colder, denser clouds embedded in a hot, volume filling medium. Modeling the colder phases with traditional methods for numerical fluid dynamics is computationally expensive since it requires to spatially resolve the comparably small clouds. The required resolutions turn out to be impossible to achieve for simulations of entire galaxies or even cosmological simulations. Yet, the latter provide a much greater degree of realism, a more complete picture of the galaxy formation history and are simpler to compare to observational data, making them a valuable tool in modern galaxy formation research. To be able to predict the properties of warm and cold gas phases in the next generation cosmological galaxy formation simulations, we use our knowledge of the multi-phase structure of interstellar and circum-galactic gas and apply multi-fluid techniques to treat different gas phases as separate fluids, coupled by mass exchange, drag, and heating from feedback processes. These coupling terms are the small-scale closure to the simulation and represent volume-averaged behavior of unresolved processes. I will present first results in the application of this technique to the galactic outflows, warm clouds in turbulent atmospheres, and the interstellar medium.