碎波誘導流에 의한 流體力의 數値解析 = Numerical Analysis on the Fluid Force by Breaking Wave Induced Currents

다국어 초록 (Multilingual Abstract)

Korea Ocean Research and Development Institute performed the basic design of Ear-Do Ocean Research Station in 1998. The design wave was taken to be the deep water wave which was obtained through wave hindcasting procedure. Wave forces acting on the structure were calculated by Morison formula utilizing the stream function theory of 5th order. The three dimensional model testing with NNW deep water wave direction gave the results such that the occurrence of breaking waves over the peak of Ear-Do caused very small wave height at the structure position. However, the measured wave forces were greater than the calculated forces based on deep water wave height. Furthermore, it was also perceived that the time series of the forces looked like corresponding to the case where waves were superimposed by an unidirectional current. In the present study, the current is presumed to be a flow secondly induced by breaking waves, and an extensive study to clarify the current in a quantitative sense is performed through numerical analysis and hydraulic experiment. The results showed that a strong circulation can surely occur in the vicinity of the structure due to radiation stress differentials given by the breaking waves. It was also recognized that the velocity of the induced current varied with the magnitude of energy dissipation rate introduced in the numerical analysis. The numerical analysis was tuned adjusting the dissipation rate so that the calculated wave field could closely match with the experimental results. The fluid force (in prototype) for the optimal match showed approximately 2.2 % increase over the calculated value based on the deep water wave height (24.6 m) whereas the force corresponding to the average of the experimental value showed the increase of about 13.0 %.

목차 (Table of Contents)

• 1. 서론 = 1
• 1.1 연구 배경 = 1
• 1.2 연구과제의 목표 = 4
• 1.3 연구 내용 및 범위 = 4
• 2. 쇄파유도류 계산을 위한 수치해석 = 6
• 2.1 개요 = 6
• 2.2 파랑전파 및 방사응력의 결정 = 6
• 2.3 쇄파유도류의 계산 = 11
• 3. 이차원 수리모형실험 = 13
• 3.1 개요 = 13
• 3.2 실험파 설정 = 16
• 3.3 실험안 및 계측항목 = 17
• 3.4 결과분석 및 검토 = 17
• 3.4.1 실험결과 = 17
• 3.4.2 파랑과 흐름의 복합 유체력 특성 = 18
• 4. 수치해석 결과의 적용 및 검증 = 21
• 4.1 에너지 감쇠계수와 쇄파의 전파속도 = 21
• 4.2 이차원 적용 = 24
• 4.3 삼차원 적용 = 27
• 4.4 유체력 계산 = 33
• 4.5 구조물 설계 시 SACS의 이용기법 제시 = 37
• 5. 결론 = 41
• 참고문헌 = 43
• 부록 = 45
• A. SACS 해석결과 (이어도 NNW 종단면) = 46
• B. λ값 변화에 따라 삼차원 수치해석 결과 = 51