For each model, we relax a steady-state Soblev solution which we use as the initial state of the time-dependent LDI simulation. The lower boundary follows Runacres & Owocki, fixing the density \(\rho_0\) according to the expected CAK mass loss rate and making adjustments for finite disk, ionization, and line strength cutoff corrections. We start the simulation at approximately sonic point, at 1.01 \(R_*\).
There is also significant empirical evidence that the stellar atmosphere below the sonic point has some variability. We thus vary the density at the lower boundary with a periodic perturbation of amplitude \(0.1 \rho_0\) and period 4000 seconds, choosing these parameters according to Sundqvist 2013.