John H. Nath, Koji Kobune


Large waves in a series of random ocean waves are considered in the design of ocean structures. When random structural vibrations can be ignored, periodic wave theories are used to predict the water particle kinematics for a design wave even though the real wave is irregular. This paper presents the authors' first attempt to quantify the validity of using periodic wave theory for random waves. Measurements of maximum horizontal and vertical velocities were made in laboratory generated periodic and random waves. They compared favorably with predictions from periodic wave theories (even with Airy theory) particularly for the large waves in a series. Since the design wave concept is applied to the largest waves, the conclusion is that periodic wave theory may be adequate, providing an appropriate factor of safety is used to account for the differences between the actual maximum wave kinematics in nature and those in the predictive theory.


random wave; periodic theory; velocity; velocity prediction

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