Abstract
When operating with a moonpool, a main concern is the large-amplitude piston-mode motion at resonance. This limits the time-window for operations inside the moonpool. Longer time-windows are desired. Further, the moonpool size is expected to increase for dedicated vessels. There has therefore recently been an increased attention to moonpool design. Potential theory highly over-predicts the water motion at moonpool resonance, and may not be used for analyzing moonpool. Viscous damping has been shown to be important, and hence vital for the moonpool functionality. We present new numerical results with a hybrid method that combines potential and viscous flow. The simulations are done with a newly implemented code called PVC3D (Potential Viscous Code). The free-surface motion is governed by potential theory, while a Navier-Stokes solver provides the solution in the main bulk of the water. With the presently considered set-up with simple geometries, the computational time remains similar to that of pure potential flow time-domain solvers, while the important flow separation that provides viscous damping is captured. The application is to a 3D moonpool set-up. The inlet of the moonpool has sharp corners, and viscous damping is significant. Good agreement with experiments is demonstrated.