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Description:
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A comprehensive experimental study was conducted to produce benchmark wave
kinematics data for five different regular waves and the maxima of four different irregular
wave trains . Two of the irregular waves generated are in the category of rogue waves . A
series of experiments were conducted in a 2 -D wave tank at Texas A &M University to
measure wave velocities and accelerations using LDV and PIV systems . The wave crests
of regular and rogue waves are the focus of this study . With the measured wave velocity
field , the wave accelerations were computed using a centered finite difference scheme .
Both local and convective components of the total accelerations are obtained from
experimental data . Also , the nonlinear wave forces on a truncated slender cylinder are
computed by applying the obtained wave kinematics to the Morison equation . The force
results based on measured wave kinematics are compared with those based on the
kinematics of linear extrapolation , Wheeler stretching , and modified stretching . The
Wheeler stretching method generally underestimates the actual wave kinematics . The
linear extrapolation method is very sensitive to the cutoff frequency of the wave spectrum .
The modified stretching method tends to predict the maximum value of wave kinematics
above the still water level (SWL ) well except for the convective acceleration . The magnitude of convective acceleration in the regular waves was negligibly small , whereas
the magnitudes of horizontal and vertical convective accelerations in the rogue wave were
increased rapidly above the SWL . |