1. Computational Codes: In a companion computational tool development program for wing-body stage separation3, a significant effort has been expended on merging two existing versions of the OVERFLOW Navier-Stokes flow solver. The resulting code is referred to as OVERFLOW 2, and includes the capabilities and features of OVERFLOW-D and OVERFLOW Version 1.8, enabling a fully-viscous, 6-degree-of-freedom, multi-body simulation capability. The Chimera overset structured grid scheme is employed,18which is well suited for multiand moving-body applications because the grids attached to each body need only be reconnected when the bodies are moved, rather than being regenerated. The OVERFLOW-D code is the result of extensive development for a dynamic, moving-body simulation capability.19,20,21This capability has been demonstrated on a number of applications, including store separation, rotorcraft, and missile problems. OVERFLOW-D includes 6-degree-offreedom dynamic motion, automatic background grid generation, fast hole-cutting and grid connectivity, and parallel computation via the MPI (Message Passing Interface) library. In comparison, the standard OVERFLOW flow solver (versions 1.6-1.8)22,23has been used for applications such as launch vehicles, subsonic transports, and hypersonic stage separation. Enhancements to this code have included grid sequencing and multigrid acceleration, low-Mach preconditioning, multiple species capability, implementation of several 1- and 2-equation turbulence models, and addition of Newton sub-iteration and dual time-stepping algorithms. Parallel computation has been accomplished using multi-level parallelism (MLP) and MPI. Of specific interest here is the use of multigrid and grid sequencing for faster convergence of steady-state problems, and the combination of dual time-stepping with OVERFLOW-D capabilities for
2. Quantitative Proximity Data: Longitudinal aerodynamic characteristics, CN, CA, and Cm, for the LGBB booster and orbiter models in belly-to-belly proximity at M=6 are presented in Figures 8-14. Each plot includes companion isolated data for the corresponding model. Figures 8, 9, 12, 13, and 14 present coefficient data over the range of longitudinal (streamwise) X-separation locations tested in the 20-Inch Mach 6 Tunnel (Fig. 4) for a fixed vertical (spanwise) Z-separation proximity location. Figures 10 and 11 present coefficient data over the range of vertical Zseparation locations for a fixed longitudinal X-separation location. Each data point in these plots corresponds to a different tunnel run with models at a nominal angle of attack of zero degrees. Figures 8-11 include steady, viscous computational data generated using OVERFLOW code (The reader is referred to Ref. 3 for details on the computational tool development effort)