절단계류된 K-Semi의 저 주파수 Pitch 운동에 관한 수치해석 연구

Abstract

This study investigated the low-frequency pitch motion for K-semi (KRISO standard semi-submersible) moored with a truncated mooring system. The comparison was carried out with the model test results performed in the Ocean Engineering Basin of KRISO. In the model test, a 1/50 scaled model structure was installed with 12 truncated mooring lines. The model was tested with several wave conditions under regular and irregular waves. Low-frequency pitch motion was especially observed with a large horizontal motion in irregular waves. A Numerical study investigated the low frequency pitch motion related to horizontal motion in waves. An in-house program was utilized to carry out the numerical simulation. The hydrodynamic force was calculated with AdFlow based on HOBEM in the frequency domain. Time domain simulation was performed with KIMAPS based on Cummins’s method including wave drift force, fluid drag force and mooring force. From the numerical simulation, slowly-drift low-frequency motion was investigated by conducting the simulation under various mooring systems. The effects of second-order drift force and fluid drag force were also studied on low-frequency pitch motion and mooring tension responses.