On damping of two-dimensional piston-mode sloshing in a rectangular moonpool under forced heave motions

Based on a similarity between piston-mode sloshing in a two-dimensional rectangular moonpool and a small-amplitude oscillatory flow through a slot in a slatted screen, a pressure discharge in the moonpool opening is theoretically quantified. This makes it possible, by changing the dynamic free-surface condition inside the moonpool, to account for the vortex-induced damping and thereby to modify the inviscid potential flow statement. The present paper is an important addition to Faltinsen et al. (J. Fluid Mech., vol. 575, 2007, pp. 359-397), where a discrepancy between the potential flow theory and model tests was reported. New calculations are supported by the earlier model tests of the authors as well as numerical data obtained by means of viscous solvers.