We use the numerical hydrodynamics code VH-1 (Blondin et al.) modified to include line driving and radiative cooling. These features remain essentially the same as described in Sundqvist 2013. We apply radiative cooling through the energy equation and cooling function from Runacres & Owocki 2002, and impose a floor temperature of \(40 \, 000\) K to mimic UV photoionization.

The line driving computations have been only slightly modified to port it from Fortran 77 to Fortran 90. The basic method remains the same as in Owocki 1991a, and Owocki & Puls 1996. Line driving in these winds relies on Doppler shifting to leverage the absorption from optically thick lines, but this results in strong non-local effects within the wind. To capture this phenomenon without doing computationally expensive radiation transport, we use the Smooth Source Function method (SSF) which accounts for absorption between the wind and star, as well as radial, scattered diffuse radiation. We also apply the Eddington limb darkening described in Sundqvist 2013.