In this study, the analysis of 2DOF (2 Degree Of Freedom) motion and added resistance of a ship in regular head waves is carried out using RANS (Reynolds Averaged Navier-Stokes) approach. In order to improve the accuracy for large amplitude motions, the dynamic overset scheme is adopted. One of the dynamic overset schemes, Suggar++ is applied to WAVIS which is the in-house RANS code of KRISO (Korea Research Institute of Ships and Ocean Engineering). The grid convergence test is carried out using the present scheme before the analysis. The target hull form is KRISO VLCC tanker (KVLCC2) and 13 wave length conditions are applied. The present scheme shows the improved results comparing with the results of WAVIS2 in the non-inertial reference frame. The dynamic overset scheme is confirmed to give the comparatively better results for the large amplitude motion cases than the non-inertial frame based scheme.
인접한 블록과 공유하는 경계에서 동일한 점을 유지하기 때문에 격자 간 자료 전달 과정에서 별도의 변환, 내삽 등의 과정을 거치지 않고 직접 전달함으로써 해의 정확도를 유지할 수 있는 장점이 있으나, 특정부분에만 격자점을 밀집시키거나 격자분포를 유연하게 조정하기 어려운 단점이 있고, 물체가 운동하는 경우에는 매 시간간격마다 격자를 재생성하거나, 비관성 좌표계를 활용하는 수밖에 없다
일반적으로 사용되는 다중블록 격자계(multi-block grid system)는 인접한 블록과 공유하는 경계에서 동일한 점을 유지하기 때문에 격자 간 자료 전달 과정에서 별도의 변환, 내삽 등의 과정을 거치지 않고 직접 전달함으로써 해의 정확도를 유지할 수 있는 장점이 있으나, 특정부분에만 격자점을 밀집시키거나 격자분포를 유연하게 조정하기 어려운 단점이 있고, 물체가 운동하는 경우에는 매 시간간격마다 격자를 재생성하거나, 비관성 좌표계를 활용하는 수밖에 없다. 격자 재생성 방법은 복잡한 3차원 형상에 적용하기 곤란하며, 비관성 좌표계를 이용하면 운동 변위가 큰 경우에 적용하는데 실용적 한계가 있다.
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동적 중첩격자 기법을 이용한 KVLCC2의 파랑중 부가저항 및 2자유도 운동 해석
大韓造船學會 論文集 = Journal of the Society of Naval Architects of Korea
v.55 no.5 = no.221
, 2018년, pp.385 - 393
( 선박해양플랜트연구소 )
( 선박해양플랜트연구소 )