This paper provides an overview of the computational fluid dynamics analysis of the ascent of the Space Shuttle Launch Vehicle during the investigation of the STS-107 accident. The analysis included both steady-state and unsteady calculations performed with the Overflow and Cart3D flow solvers. The unsteady calculations include moving body, six degree-of-freedom simulations of foam debris shed from the region of the left bipod-ramp of the vehicle. Many such debris trajectories were computed, some of which impacted the vehicle. The analysis provided an estimate of the speed at which such a piece of debris would strike the wing leading edge of the Shuttle Orbiter. These results were supplied to the Columbia Accident Investigation Board, and guided the choice of the impact velocity and foam size selected for the foam-firing test done as part of the investigation. This testing subsequently showed that it was possible for a piece of foam debris to cause massive damage to the Shuttle Orbiter wing Reinforced-Carbon-Carbon panels and T-seals, creating a breach where hot gases could enter the wing structure during reentry.

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An algorithm for surface domain decomposition and grid generation for overset grids is described. A complex surface domain is covered by t wo t ypes of grids: seam grids and block grids. Seam grids are grids used to wrap around surface crease lines and regions of high surface curvature. Block grids are grids that cover the remaining surface regions not occupied by the seam grids. The seam and block grids form a set of overlapping surface grids that cover the entire surface geometry. Given a set of seam grids, an automated method for generating the block grids is presented in this paper. Examples of seam and block grids are given for several con gurations including the V-22 tiltrotor fuselage and the X-CRV Crew Return Vehicle.

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