Experimental and numerical investigation of wave resonance in moonpools at low forward speed

•Moonpool wave resonance at low forward speed.•New numerical method combining potential flow and viscous flow.•Applying harmonic polynomial in cell method and the finite volume method.•Extensive 2D model test campaign on a moonpool section.

In order to study the behavior of resonant piston-mode resonance in a moonpool at low forward/incoming current speed, we performed a series of experiments and compared them to a nonlinear hybrid method which couples potential and viscous flow. The setting is a 2D box section with a moonpool gap in the middle, forced to oscillate in heave with a given amplitude and frequency, while simultaneously travelling at a given constant forward speed. The numerical method couples a Navier–Stokes (CFD) solver using the Finite Volume Method (FVM), with a potential flow method using the Harmonic Polynomial Cell method (HPC). It is found that the moonpool behavior is slightly reduced with a low forward velocity, and the reduction is dependent on the heave forcing amplitude.