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Physical Modeling of a Floating Breakwater with a Membrane

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Master's thesis

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A physical model study of a floating breakwater with an attached vertical membrane was conducted. The objective was to determine if the wave protection provided by a floating breakwater can be improved by the addition of a membrane. The wave transmission characteristics were analyzed for nine different structural configurations. The different configurations examined the compliance of the moorings and the length, position, and permeability of the membrane. The nine configurations were tested at 8 different wave periods ranging from 0.5 seconds to 1.2 seconds and each test was performed twice. Thus, 72 combinations were examined and approximately 150 flume runs were completed to collect data for this project. The average transmission coefficient for each of the nine cases ranged from 0.705 to 0.853. In all cases tested, the addition of a membrane to the floating breakwater reduced the transmitted wave height relative to the structure with no membrane. The average wave transmission coefficient was 0.85 for the structure with no membrane. The average far all the configurations with a membrane was 0.75, or about a 12 reduction. The most effective membrane configuration gave a reduction of 17. For the breakwater configurations and wave conditions tested, the following results were observed 1 a membrane that is 14 of the water depth in length is more effective than membrane lengths of 12 the depth and the full depth in length, 2 lower transmission was obtained by placing the membrane at the lee side of the structure rather than the front or center, 3 a permeable membrane is more effective than an impermeable membrane, and 4 elastic mooring lines had a lower transmission than stiff moorings. 13 tables, 53 figures, 26 photographs, 16 refs.

Subject Categories:

  • Physical and Dynamic Oceanography
  • Civil Engineering

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