  The vertical shear instability (VSI) is a source of hydrodynamic turbulence
that can drive vigorous vertical mixing and moderate levels of accretion in
protoplanetary disks, and it could be observable in the near future. With
high-resolution three-dimensional numerical hydrodynamics simulations, we
modeled the behavior of the VSI in protoplanetary disks with and without
embedded planets. We then measured its accretion and mixing capabilities by
comparing the full Reynolds stress, which includes the contribution of
nonaxisymmetric features, such as spiral arms and vortices, to the Reynolds
stress due to the azimuthally averaged velocity field, which can be attributed
to good approximation to the VSI. We verified that the VSI can contribute to
the accretion stress and showed that, depending on disk conditions, an embedded
planet can coexist with or suppress VSI turbulent stress. Specifically, the
presence of spiral shocks launched by a planet or planet-generated vortices can
interfere with the VSI near the planet's vicinity, with the instability
recovering at large enough distances from the planet or vortex. Our results
suggest that observations of VSI signatures are unlikely in disks that contain
massive, nonaxisymmetric features.
