  We examine the evolution and influence of viscosity-induced diskoseismic
modes in simulated black hole accretion disks. Understanding the origin and
behavior of such oscillations will help us to evaluate their potential role in
producing astronomically observed high-frequency quasi-periodic oscillations in
accreting black hole binary systems.
  Our simulated disks are geometrically-thin with a constant half-thickness of
five percent the radius of the innermost stable circular orbit. A
pseudo-Newtonian potential reproduces the relevant effects of general
relativity, and an alpha-model viscosity achieves angular momentum transport
and the coupling of orthogonal velocity components in an otherwise ideal
hydrodynamic numerical treatment.
  We find that our simulated viscous disks characteristically develop and
maintain trapped global mode oscillations with properties similar to those
expected of trapped g-modes and inner p-modes in a narrow range of frequencies
just below the maximum radial epicyclic frequency. Although the modes are
driven in the inner portion of the disk, they generate waves that propagate at
the trapped mode frequencies out to larger disk radii. This finding is
contrasted with the results of global magnetohydrodynamic disk simulations, in
which such oscillations are not easily identified. Such examples underscore
fundamental physical differences between accretion systems driven by the
magneto-rotational instability and those for which alpha viscosity serves as a
proxy for the physical processes that drive accretion, and we explore potential
approaches to the search for diskoseismic modes in full magnetohydrodynamic
disks.
