  Intermediate-mass main sequence stars have large radiative envelopes
overlying convective cores. This configuration allows internal gravity waves
(IGWs) generated at the convective-radiative interface to propagate towards the
stellar surface. The signatures of these waves can be observed in the
photometric and spectroscopic data from stars. We have studied the propagation
of these IGWs using two-dimensional fully-non-linear hydrodynamical simulations
with realistic stellar reference states from the one-dimensional stellar
evolution code, Modules for Stellar Astrophysics (MESA). When a single wave is
forced, we observe wave self-interaction. When two waves are forced, we observe
non-linear interaction (i.e. triadic interaction) between these waves forming
waves at different wavelengths and frequencies. When a spectrum of waves
similar to that found in numerical simulations is forced, we find that the
surface IGW frequency slope is consistent with recent observations. This power
law is similar to that predicted by linear theory for the wave propagation,
with small deviations which can be an effect of nonlinearities. When the same
generation spectrum is applied to 3 solar mass models at different stellar
rotation and ages, the surface IGW spectrum slope is very similar to the
generation spectrum slope.
