A Chimera-based, zonal discontinuous Galerkin method Nathan A. Wukie * , Paul D. Orkwis † University of Cincinnati, Cincinnati, Ohio, 45221 Christopher Schrock ‡ Air Force Research Laboratory, Wright-Patterson AFB, Ohio, 45433 In order to achieve increased computational efficiency in a design environment, a Chimera based, zonal discontinuous Galerkin(DG) approach was developed incorporating a two- fidelity model. The higher-fidelity models solve the full advection-diffusion problem for the Navier-Stokes and Reynolds-Averaged Navier-Stokes(RANS) equations. The lower-fidelity models are reduced versions of the higher-fidelity models, where only the advection terms are retained. The distance from a solid surface was used in this study as a heuristic for applying the low/high-fidelity models in an effort to best-capture boundary layer develop- ment. The separate zones are coupled using a simple approach where only the advection terms are computed along interfaces. This approach was previously presented in the lit- erature for the Navier-Stokes equations on a discontinuous Galerkin discretization. The present work extends the approach to a Chimera-based, discontinuous Galerkin method for the RANS equations using the Spalart-Allmaras turbulence model. A 10-43% improvement in efficiency constructing the system residual and Jacobian matrix was observed using the zonal approach while producing results comparable to the full RANS approach. Nomenclature Q Solution vector  F a,d Flux vector (advective, diffusive) ψ Legendre basis polynomial Ω Element volume ρ Density u Cartesian velocity vector E Total energy ˜ ν Turbulence eddy viscosity p Pressure T Temperature τ Shear stress tensor I Identity tensor  F Aerodynamic force vector c d Drag coefficient I. Introduction I n the development of future Air Force systems, there is a pressing need for flexible and efficient, high- fidelity, multi-physics, simulation capabilities. These capabilities enable the discovery of cross-discipline * PhD Student, Dept. of Aerospace Engineering, ML 70, Cincinnati, Ohio 45221, AIAA Student Member. † Bradley Jones Professor, Dept. of Aerospace Engineering, ML 70, Cincinnati, Ohio 45221, AIAA Associate Fellow. ‡ Research Aerospace Engineer, Computational Sciences Center, AIAA Senior Member 1 of 13 American Institute of Aeronautics and Astronautics