Analysis of floating concrete breakwater mooring tension by DualSPHysics

Ocean Engineering Department, Faculty of Marine Technology, Institut Teknologi Sepuluh Nopember, Surabaya, Indonesia

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Abstract

An analysis of the effect of the distance between a Floating Concrete Breakwater (FCB) with dual configurations on the tension of the catenary mooring line system is presented. The Smoothed Particle Hydrodynamics method in DualSPHysics software was used to analyze the maximum tension on FCB mooring lines at the 1:10 model scale. The results indicate that the gap between FCBs influenced the mooring line's tension. In the narrow FCB (40cm width), the mooring line tension was reduced by 20% when the gap is reduced to 20 cm (50% width) from 30 cm (75% width) and increased by 1% when the gap was increased from 30 cm (75% width) to 40 cm (100% width). With a few exceptions, the wide FCB (102.5cm width) shows an 8% tension increase at a gap of 50cm (50%) to 75cm (75% width) and a 16% tension drop when the gap was reduced to 75cm (75% width) from 1 m (100% width). The wave’s height and periods also influence the mooring line tension. At a wave height of 0.18 meters and 2.21 seconds wave period of 2.21 s, the maximum tensions for a narrow single FCB were 187.54 kN at the fairlead and 185.189 kN at the anchor. At a wave height of 0.28 m and a wave period of 2.84 s, the maximum tensions of the wide single FCB is 359.75 kN at the anchor and 362.42 kN at the fairlead. In the dual configuration, the maximum tension was recorded when the gap between the floating breakwaters was 50% of the width, either for the narrow or wide FCB.