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1994 Fiscal Year Final Research Report Summary

Hydrodynamic interaction of multiple-cylinders oscillating in both current and waves

Research Project

Project/Area Number 05650949
Research Category

Grant-in-Aid for General Scientific Research (C)

Allocation TypeSingle-year Grants
Research Field 海洋工学
Research InstitutionUniversity of Tokyo

Principal Investigator

BAO Weiguang  University of Tokyo, Institute of Industrial Science Research Associate, 生産技術研究所, 助手 (90238220)

Co-Investigator(Kenkyū-buntansha) KINOSHITA Takeshi  University of Tokyo, Institute of Industrial Science Associate Professor, 生産技術研究所, 助教授 (70107366)
Project Period (FY) 1993 – 1994
KeywordsWave drift damping / Wave drift force / Slow drift motion / Nonlinear wave load
Research Abstract

Ocean structures, most of which are constructured by multiple vertical cylinders, are working in an environment of both waves and current. In order to evaluate the hydrodynamic forces acting on the ocean structures, the interaction between the waves and current as well as between multiple cylinders has to be considerded. Once the wave drifting force caused by waves and current is calculated, we can obtain the wave drift damping which plays an important role in the slow drift motion of floating body moored in irregular waves. In the present research, the current velocity is assumed to be small (compared with the phase velocity of waves). The effect of the current and the importance of the interaction waves near the cylinders are investigated. The research results are as follows.
1.A mathematical model is established, which takes account of interaction among multiple cylinders fixed or oscillating in both waves and current. A semi-analytical solution is obtained. A computer program based … More on the above theory is developed, which can calculate the first and second order hydrodynamic forces for different current velocity, wave frequencies, wave direction, cylinder number and arrangement.
2.In order to verify the theory and calculated results, experiments in wave tanks were carried out. The experimental results are in good agreement with the calculated ones.
3.The steady disturbance flow (caused by the current) has a strong effect on the second order forces such as wave drift force and wave drift damping.
4.The effect of evanescent waves scattered from cylinders can not be neglected.
5.The oscillation of the floating body has a strong effect on the second order forces near the resonance of the oscillation.
6.In a certain range of wave frequencies and wave heights (Kc number), the wave drift damping (calculated by the potential theory) is very important in the damping of slow drift motion.
In the future, the above theory is expanded to be applied to the arbitrary shaped bodies. The computer program will be developed and experiments will be carried out to verify the theory and calculated results. Less

  • Research Products

    (18 results)

All Other

All Publications (18 results)

  • [Publications] W.Bao: "Hydrodynamic Interaction among Multiple Cirular Cylinders in both Waves and Slow Current" 日本造船学会論文集. 174. 193-203 (1993)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] W.Bao: "Hydrodynamic Interaction among an Assembly of Circular Cylinders in Both Waves and Slow Current" Proceedings of 2nd Symposium on Nonlinear and Ferr-Surface Flows,K.Mori. 11-14 (1993)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] W.Bao: "Hydrodynamic Forces Acting on Multiple Circular Cylinders in both Waves and Slow Current" Proceedings of 13th International Conference on OMAE. vol.1. 63-72 (1994)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] W.Bao: "The Reciprocal Relation of Hydrodynamic Forces Acting on Floating Bodies in both Waves and Slow Current" Proceedings of 9th International Workshop on Water Waves and Floating Bodies. 15-19 (1994)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] T.Kinoshita: "Wave Drift Damping of Multiple Vertical Cylinders;Prediction and Measurement" Proceedings of International Workshop on Floating Structures in Coastal Zone. 38.1-38.18 (1994)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] T.Kinoshita: "Hydrodynamic Interaction among Freely Floating Cylinders in both Waves and Slow Current" Proceedings of 3th Symposium on Nonlinear and Free-Surface Flows. 15-18 (1994)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] T.Kinoshita: "Interaction of Freely Oscillationg Vertical Cylinders with Waves and Slow Current" Proceedings of 10th International Workshop on Water Waves and Floating Bodies. (1995)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] T.Kinoshita: "Circular Cylinders Freely Oscillating in both Waves and Slow Current" Proceedings of 5th International Conference of ISOPE. (1995)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] T.Kinoshita: "Wave Drift Damping Acting on Multiple Circular Cylinger(Model Tests)" Offshore Mechanics and Arctic 14th International Conference on Engineering. (1995)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] W.Bao, T.Kinoshita: "Hydrodynamic Interaction among Multiple Circular Cylinders in Both Waves and Slow Current." Journal of Society of Naval Architects Japan. 174. 193-203 (1993)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] W.Bao, T.Kinoshita: "Hydrodynamic Interaction among an Assembly of Circular Cylinders in Both Waves and Slow Current." Proceedings of 2nd Symposium on Nonlinear and Free-Surface Flows, K.Mori. 11-14 (1993)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] W.Bao, T.Kinoshita: "Hydrodynamic Forces Acting on Multiple Circular Cylinders in both Waves and Slow Current." Proceedings of 13th International Conference on OMAE. 63-72 (1994)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] W.Bao, T.Kinoshita: "The Reciprocal Relation of Hydrodynamic Forces Acting on Floating Bodies in both Waves and Slow Current." Proceedings of 9th International Workshop on Water Waves and Floating Bodies. 15-19 (1994)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] T.Kinoshita, W.Bao and S.Sunahara: "Wave Drift Damping of Multiple Vertical Cylinders ; Prediction and Measurement." Proceedings of International Workshop on Floating Structures in Coastal Zone. 38.1-38.18 (1994)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] T.Kinoshita, W.Bao: "Hydrodynamic Interaction among Freely Floating Cylinders in both Waves and Slow Current." Proceedings of 3rd Symposium on Nonlinear and Free-Surface Flows. 15-18 (1994)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] T.Kinoshita, W.Bao: "Interaction of Freely Oscillating Vertical Cylinders with Waves and Slow Current." Proceedings of 10th International Workshop on Water Waves and Floating Bodies. (1995)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] T.Kinoshita, W.Bao: "Circular Cylinders Freely Oscillating in both Waves and Slow Current." Proceedings of 5th International Conference of ISOPE. (1995)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] T.Kinoshita, S.Sunahara and W.Bao: "Wave Drift Damping Acting on Multiple Circular Cylinder (Model Tests)." 14th International Conference on Offshore Mechanics and Arctic Engineering. (1995)

    • Description
      「研究成果報告書概要(欧文)」より

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Published: 1996-04-15  

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