On the Time-Mean Drift Force Acting on a Floating Offshore Structure in Wave

J. Ocean Eng. Technol. 2002;16(3):8-18.

부유식 해양구조물에 작용하는 시감평균 파표류력에 관한 고찰

홍도천

한국해양연구원 해양개발시스템연구본부

Keywords: Time-Mean Wave Drift Forces and Moments, Far-Field Method, Near-Field Formula, Non-Zero Time-Mean Momentum Flux

핵심용어: 시간평균 파표류적 및 모멘트, 무한원방방법, 접수면압력 직접적분법, 0이 아님 시간평균 유체 모멘텀

Abstract

Formulation of the far-field method for the prediction of time-mean hydrodynamic force and moment acting on a 3-D surface-piercing body in waves is reviewed. It is found that the inequality between the weight of the floating body and its buoyancy force permits the replacement of the fluid particles inside the control surface by the fluid particles outside the control surface. Under such circumstances, momentum exchanges across the control surface make the time-mean value of the time rate of the momentum of the fluid inside the control surface non-vanishing. It is a second-order quantity which is hard to calculate by the far-field method. The drift forces and moments on half-immersed ellipsoids are calculated by both the far-field method and the near-field method. The discrepancy between two numerical results is presented and discussed.