Flowchart of the MAIHEM-CLOUDY interface implemented in our hydrodynamic simulations. Starburst99 produces the radiation spectrum for the total stellar mass (M _⋆ = 2.05 × 10⁶ M _⊙) and given metallicity (Z), which is used by MAIHEM and CLOUDY. The MAIHEM Python interface calls CLOUDY to generate the CIE tables as a function of temperature for the cluster boundary and produce the background UV SED from the Starburst99 synthetic stellar spectrum to be used by NEI atomic chemistry and cooling routines in MAIHEM. Solving the hydrodynamic fluid equations, together with radiative cooling and heating functions, MAIHEM produces the outflow temperature (T _w ), density profile (n _w ), and NEI states according to the Starburst99 UV SED. The PI CLOUDY model (pure photoionization) uses only the density profile made by the first MAIHEM hydrodynamic run with an isothermal ambient temperature of 10³ K, together with the SED model produced by Starburst99. The ambient temperature profile (T _amb) predicted by the PI CLOUDY model is employed for the ambient medium in the second MAIHEM hydrodynamic run and the CPI case. The CPI CLOUDY model (photoionization + hydrodynamic collisional ionization) is calculated in the same way but uses both the temperature and density profiles of the outflow model produced by the second MAIHEM run and the ambient temperature structure from the PI model. The radiation- and density-bounded luminosities L _λ are calculated from the emissivities ϵ _λ (r) produced by the PI and CPI CLOUDY models, described in Appendix A.