Experimental investigation on gap resonance between two floating vessels

Abstract

This paper explains the influence of gap resonance phenomena in floating vessels having unequal draughts. Two separate model configurations are considered here: one is a vessel having a shallow draught at the weather side (SW), and the other is a deep draught vessel that comes at the weather side. An experimental investigation was carried out in beam sea conditions, where the vessel could only move freely in the heave and roll directions. By beam sea, we mean the incident waves come at a right angle to the broadside of the vessels. Regular wave tests reveal that even though only a slight difference in the gap resonance frequency is observed for the two configurations, the wave amplification at resonance is 57% higher for SW. The reason for this behavior is explained using the instantaneous velocity and vorticity obtained from the particle image velocimetry analysis for a selected test case. Furthermore, the turbulent characteristics of the flow inside the gap for the configurations are compared at different time instances. The horizontal force acting on the vessels and motions (heave and roll) of the vessels in the beam sea condition are also reported in the study.