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Document Type:Master's Thesis
Name:Timothy Wayne Mays
Email address:twmays@vt.edu
URN:1997/00550
Title:Three-Dimensional Analysis of Moored Cylinders Used as Breakwaters
Degree:Master of Science
Department:Civil Engineering
Committee Chair: Dr. Raymond H. Plaut
Chair's email:rplaut@vt.edu
Committee Members:Dr. Stergios I. Liapis, Co-Chair
Dr. Kamal B. Rojiani
Keywords:Breakwater, Cylinder, Vibration, Wave, Mooring
Date of defense:December 5, 1997
Availability: Release the entire work for Virginia Tech access only.
After one year release worldwide only with written permission of the student and the advisory committee chair.

Abstract:

For oblique and normal water waves at various frequencies, the use of moored cylinders as breakwaters is considered numerically using linear three-dimensional analysis. The breakwater can be used by itself for protection of small structures or as a series of cylinders to protect a harbor, shoreline, or moored vessel from the destructive energy associated with incident water waves. The breakwater is completely submerged below the free surface and is attached to the ocean floor with six symmetrically configured mooring lines. The cylinder is filled with air and the mooring lines remain taut during the structure's motion. Six degrees of freedom describe the motion of the breakwater and additional degrees of freedom are introduced as the cables are modeled with the use of lumped masses connected with springs. The fluid is assumed to be inviscid and incompressible, so that the velocity field can be written as the gradient of the velocity potential. A boundary integral method is used to solve the integral equations that define the external fluid flow. Free vibrations of the cylinder in both air and water are considered and "dry " and "wet" natural frequencies are computed. Motions caused by water waves are studied to establish the effect of certain parameters on the effectiveness of the breakwater. The transmission coefficient is shown to be somewhat misleading when compared to plots that show the spatial variation of the wave amplitude.

List of Attached Files

ch1and2.pdf ch3.pdf ch4.pdf
ch5figs.pdf ch5txt.pdf ch6figa.pdf
ch6figb.pdf ch6txt.pdf ch7figs.pdf
ch7txt.pdf ch8.pdf end.pdf
intro.pdf

At the author's request, all materials (PDF files, images, etc.) associated with this ETD are accessible from the Virginia Tech network only.


Date item approved:
12/19/97