Validation of Reynolds-averaged Navier-Stokes simulations for International America's Cup Class spinnaker force coefficients in an atmospheric boundary layer

Three semirigid models for International America's Cup Class spinnakers were tested in a wind tunnel with a simulated atmospheric boundary layer. These experiments were also simulated using a commercial Reynolds-averaged Navier-Stokes (RANS) solver with three different turbulence models. A comparison between the experimental and numerical force coefficients shows very good agreement. The experimentally measured differences in the driving force coefficients among the three sails were predicted well by all three turbulence models. The realizable k-ε model produced the best results, and the standard k-ε model produced the worst. The Reynolds stress model did not perform significantly better than the standard k-ε model. The results suggest that RANS can be used as a design tool for optimizing spinnaker shape.