Design Optimization of Subcavitating Hydrofoils for America's Cup Class Yachts

The optimization process did not involve any drastic measures; however, we focused on significant iterations in the SNOt framework. During the line search, we explored various options, including substantial steps. For instance, at iteration 4, a notable step was taken, as illustrated. The challenge lies in ensuring that the Computational Fluid Dynamics (CFD) converges successfully, meaning that both the N CFD and the mesh must operate without failure. Although there may be questions regarding instances of NaNs and failures, I will only present the successful outcomes.

For a specific geometry and case where we have extensive experience, the process becomes routine and reliable after fine-tuning a few parameters. Notably, this optimization typically requires less than an hour to complete, often performed on a MacBook Pro with a 12-core M1 chip, and likely even faster on the M4. This optimization encompasses multiple points and involves numerous constraints, each associated with an adjoint, which makes the effort worthwhile.

Regarding the cavitation bucket, we successfully shifted it significantly to the right. The dashed green line indicates this adjustment, moving the solid line accordingly. The black points represent our specified conditions, which demonstrate that we achieved the desired placement for the bucket. Importantly, all configurations remain feasible concerning the requested speeds for the cavitation bucket.

Overall, this optimization was accomplished with minimal drag penalty. As previously mentioned, there was a slight drag penalty observed, but the overall drag polar remains favorable.