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Numerical simulations of thermally driven convection which include both an upper convectively unstable layer and a lower stable layer have been performed in order to study the phenomenon of convective overshooting. 3-D simulations at a grid resolution of 128 zones in each dimension have been performed using the PPM hydrodynamics code. PPM treats the compressibility of the gas explicitly in this layer over which the density varies by roughly a factor of 30. The problem is initially set up in a 1-D static state with small velocity perturbations. In the unstable upper layer, a slightly super-adiabatic temperature gradient is initially applied. This initial temperature distribution is close to that which develops from the action of the convective instability, and therefore the system settles into a statistically steady state relatively rapidly. Animations of our perspective volume renderings of these 3-D compressible, penetrative convection flows will be shown.
This work is supported by the National Science Foundation under the Grand Challenge Application Group for Coupled Fields and Geophysical and Astrophysical Fluid Dynamics, grant ASC-9217394.
