The Explicit Planetary Isentropic-Coordinate General Circulation Model (EPIC GCM) is designed to create a common GCM for all known planetary atmospheres. Originally conceived as a model for the gas giants, expansion to terrestrial planets has been ongoing through the use of a hybrid vertical coordinate shifting between a flow-following isentropic coordinate to a terrain-following pressure coordinate. Although to date this model has been used primarily for research on atmospheric phenomena, these models can potentially be applied in the future to the dynamic simulation of spacecraft in planetary atmospheres like the Galileo and Huygens probes.

A key challenge in this transformation has been the incorporation of a turbulence modeling scheme. Turbulence modeling is critical for proper representation of the planetary boundary layer, accurate simulation of smaller scale-features in shear and unbounded flows, and the suppression of sub-grid-scale wave motion that leads to numerical instabilities. The currently implemented turbulence approaches under consideration are the Detached Eddy Simulation (DES) models based on the Spalart-Allmaras and Menter SST Reynolds-Averaged Navier-Stokes (RANS) models. The hybrid nature of these models allows for a unified approach to turbulence across all altitudes and all planets. We will present details on the current methodology used to implement the models as well as some sample results using hybrid turbulence.