Navier-Stokes based Unsteady Aerodynamic Computations of Launch Vehicles undergoing Forced Coupled Oscillations

A procedure is presented to accurately model transient motions of launch vehicles associated with complex flow conditions. The flow is modeled using the Reynolds-Averaged NavierStokes equations with the one-equation Spalart-Allmaras turbulence model. An overset grid system with a curvilinear near-body grid and a Cartesian off body is used. Solution quality is assessed using grid sensitivity and time-step convergence studies. Validation computations are made for a clean configuration model of the Saturn V launch vehicle for rigid-body transient motions in both the longitudinal and lateral directions, which are typically encountered during launch vehicle ascent. The effect of these transient motions on the unsteady aerodynamic response is studied. Unsteady aerodynamic response surfaces are efficiently computed using a massively parallel computer system.