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Dynamics of single point ocean moorings of a buoy : a numerical model for solution by computer

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Title Dynamics of single point ocean moorings of a buoy : a numerical model for solution by computer
Names Nath, John H. (creator)
Date Issued 1969-07 (iso8601)
Abstract A numerical model was developed which predicts the dynamic
response of a single mooring line and a buoy of forty feet diameter
to sinusoidal waves, wind and current in all deep waters. All forces
and reactions were considered to be in one plane.
The basic equations for the mooring line motion were obtained by
considering a small element of the line in terms of the conservation of
momentum and mass and the continuity of the line filament. The
resulting partial differential equations were numerically integrated by
first a transformation followed by application of the method of characteristics.
A non-linear stress-strain diagram was used. The boundary
conditions were that no motion occurred at the anchor except rotations
and the motion of the upper end of the line was the same as the motion
of the attachment point of the buoy.
The buoy was considered to be a rigid body and accelerations
were determined from Newton's second law of motion. Recurrence
formulas determined displacements and velocities.
A comparison with some prototype information was made. Transfer
functions between wave spectra and line tension spectra were available
for a mooring in 13, 000 feet of water near Bermuda. The same transfer
functions were developed with the numerical model and good agreement
was achieved. Frequency response curves for the moored buoy in pitch and
heave were also obtained and the results show that one dimensional wave
spectra obtained by double integration of the vertical acceleration of the
buoy are valid.
Genre Technical Report
Topic Oceanographic buoys
Identifier http://hdl.handle.net/1957/8451

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