A series of Navier-Stokes simulations of a complete Boeing 777-200 aircraft con gured for landing is obtained using a structured overset grid process and the OVERFLOW CFD code. At approach conditions, the computed forces for the 777 computation are within 1.5 of experimental data for lift, and within 4 for drag. The computed lift is lower than the experiment at maximum-lift conditions, but shows closer agreement at post-stall conditions. The e ect of sealing a spanwise gap between leading edge elements, and adding a chine onto the nacelle is computed at a high angle of attack. These additions make a signi cant difference in the ow o ver the wing near these elements. Detailed comparisons between computed and experimental surface pressures are shown. Good agreement is demonstrated at lower angles of attack, including a prediction of separated ow on the outboard ap. Introduction Calculating the viscous uid ow over a high-lift Aerospace Engineer. y Chief, Aerospace Operations Modeling O ce. Senior Member AIAA. z Principal Engineer. x Principal Engineer. Senior Member AIAA. Engineer Scientist Specialist. Member AIAA. k Research Engineer.

A n umber of grid-generation and CFD-process software tools have been developed which greatly improve the ability to perform overset CFD analysis of complex con gurations. These tools have been applied to the task of generating grids and computing the ow eld about two di erent high-lift aircraft con gured for landing: a Boeing 777-200, and a High-Wing Transport with externally blown aps. The high-lift ow-elds of both aircraft were simulated using the OVERFLOW solver. A N a vier-Stokes simulation of a complete Boeing 777-200 aircraft con gured for landing was obtained in less than 50 labor days with a lift coe cient which di ers from experimental data by only 1.2. This is an order of magnitude reduction in the cycle time for the entire computational process compared to a similar high-lift simulation e ort that took place two y ears earlier. The new software was utilized to perform a ow-eld analysis of a ap-rigging modi cation for the Boeing 777-200 aircraft in only four days. The software was also utilized to simplify Aerospace Engineer. y Chief, Aerospace Operations Modeling O ce. Senior Member AIAA. z Research Engineer. x Principal Engineer. Senior Member AIAA. Engineer Scientist Specialist. Member AIAA. k Principal Engineer.

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An effort to develop and integrate grid-generation and flow-solver tools capable of computing the flow over a commercial subsonic aircraft in a high-lift configuration is described. An overset-grid approach is utilized. Surface grids are generated using the Boeing Aero-Grid-and-Paneling-System plus the NASA Chimera-Grid-Tools package. Volume grids are efficiently generated using new enhancements to the HYPGEN hyperbolic-grid program and a new localelliptic grid generator. The overset grids are linked together using the PEGASUS software and automatically generated hole-cutting surfaces, which are necessary for dealing with the small gaps between high-lift elements. The grid-generation system is applied to a Boeing 747PD high-lift configuration, and the flow field is computed using the OVERFLOW program. The computed lift-coefficient result for an angle-ofattack of 8 deg is in agreement with an experimental value.