1. OVERFLOW Using OVERFLOW version 2.0y Shared, distributed and hybrid parallel processing schemes available with MPI and OpenMP Wide range of applications: – e.g., rotary and fixed-wing aircraft, wind turbines, launch and re-entry vehicles.

2. OVERFLOW (cont’d) Solves compressible NS on overset, block- structured static and/or dynamic grids – 1 st -order implicit finite-difference scheme Suite of factorized ADI schemes: e.g., scalar penta-diagonal, block tri-diagonal, etc. – 2 nd -order temporal accuracy achieved with Newton or dual-time sub-iterations. Iterate till L 2 -norm of RHS residual drops O(3). – 2 nd or 4 th -order spatial derivatives on both right and left hand operators. – 2 nd and 4 th -order explicit dissipation for stability.

3. OVERFLOW (cont’d) Overset grid method employs 2 nd -order accurate interpolation method across grid interface – Balance between accuracy and interpolation stencil size. – Interface interpolated values (i.e., fringe points) treated explicitly requiring temporal sub-iterations for convergence. – Overset method allows limited adaptive mesh refinement and 6 DOF grid motion.

4. Uniform Cartesian Background Grid Body Conforming Grid OVERFLOW (cont’d)

5. 6 DOF grid motion for wind turbine applications

6. OVERFLOW (cont’d) DES/LES modifications from DARPA Quite Helicopter Program (QHP) – Duque et al., AIAA Paper 2006-1068 Currently using hybrid RANS/LES model combining k-  SST (uRANS) and k-  (LES) following Sanchez et al. (2006). – k-  model coefficients (e.g., C  and C  assumed globally constant Kinetic Energy Simulation (KES) available – k-kl model dynamically switches from RANS to LES based on modeled length scale (l) following Shelton et al. (2006). – Dynamic coefficient evaluation results presented in near future