The effects of stellar feedback processes from massive stars, e.g. ionising radiation, winds and supernovae feedback, on the Interstellar Medium (ISM) is a debated topic. Theoretical and numerical work has shown that these processes play an important role in: regulating the star formation rate in galaxies, shaping the ISM through turbulence and ejecting baryons from galaxies via large scale outflows, among other things. I will present a new suite of high resolution hydro+N-body simulations of isolated Milky Way and LMC-like disc galaxies, using the code RAMSES. The aim is to explore the affects of stellar feedback on the ISM, quantify these effects and compare to observations of a range of nearby galaxies. I give special attention to the following topics:

-A novel extension of the traditional stability analysis (e.g. Toomre 1964), accounting for gas turbulence, applying this model to our numerical simulations and contrast these with data from The HI Nearby Galaxy Survey (THINGS) and the HERA CO Line Extragalactic Survey (HERACLES). We are able to show how this more robustly quantifies the scales of instability in the ISM and better differentiate between different ISM models.

-Using power spectra of the density and velocity fields from simulations and observations, we are able to study the scale at which energy predominantly is injected, e.g. large scales (galactic) driving or small scales (feedback) driving and how this energy is transported between scales, allowing us to better constrain the way in which feedback operates in galaxies.