Computational Fluid Dynamics (CFD) plays an ever increasingly important role in the design and analysis of racing sailboats and in particular America's Cup yachts. The pervasiveness of CFD in the design process is demonstrated by a wide range of applications, concentrating on hull and underwater appendage design, from two of the US syndicate entries, Young America and AmericaOne, from just completed America's Cup 2000 races in Auckland, NZ. The CFD methods employed generally span a wide range, but the freesurface panel method SPLASH and the overset NavierStokes code Overflow are highlighted here. Discussion includes the CFD tools employed, how they are made to fit into the design process, and specific applications directed at hull and appendage design.

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The SPLASH free-surface potential flow panel code computer program is presented. The 3D flow theory and its numerical implementation are discussed. Some more conventional applications are reviewed, for steady flow past solid bodies, and for classical linearized free-surface flow. New free-surface capabilities are also described, notably, steady nonlinear solutions, and novel unsteady partially­nonlinear solutions in the frequency domain. The inviscid flow method treats both free-surface waves and lifting surfaces. The calculations yield predictions for complex interactions at heel and yaw such as wave drag due to lift, the effect of the free­surface on lift and lift-induced drag, and unsteady motions and forces in oblique or following seas. These are in addition to the usual predictions for the simpler effects considered separately, for example double-body lift and induced drag, and upright steady wave resistance or added resistance in head seas. For prediction of total resistance, the use of computed variable wetted areas and wetted lengths in a standard semi-empirical, handbook-type "viscous stripping" algorithm provides a more accurate estimation of viscous drag than is possible otherwise. Results from a variety of IACC and IMS yacht design studies, including comparisons with experimental data, support the conclusion that the free­surface panel code can be used for reliable and accurate prediction of sailboat performance.

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Kestrel is a fixed wing multi-physics computational based engineering (CBE) product of the High Performance Computing Modernization Program (HPCMP) Computational Research and Engineering for Acquisition Tools and Environments-Air Vehicle (CREATE TM -AV) project. Kestrel offers many advanced features including mesh deformation for moving control surfaces, aeroelastic coupling, propulsion integration, overset analysis, and prescribed motion of multiple bodies that can be very useful for a variety of aircraft applications. To help ensure that these capabilities are as robust and accurate as possible, various fundamental physics validation cases were tested. This paper covers the results of the two-dimensional (2D) test cases, including: NACA-0012 Airfoil, NACA-64A010 Airfoil, Backward Facing Step, Flat Plate, and Base Flow. Results were compared to test data, results from other software packages, and analytical methods. There was good agreement between the CREATE TM -AV Kestrel results and the comparison data. Nomenclaturefriction coefficient M = Mach number c = chord V ∞/ref = freestream velocity α or AOA = angle of attack Re = Reynolds Number