NEAR-SURFACE ORBITAL VELOCITIES IN IRREGULAR WAVES

K.-F. Daemrich, A. Gotschenberg

Abstract


The paper deals with measurements of horizontal orbital velocities near the surface of mechanically generated waves in a wave flume. Due to the characteristics of most velocity probes, it is difficult or impossible to measure with a fixed probe in the area above the lowest trough. As the probe is not submerged continuously, failures or uncertainties in the measurements may occur. To overcome these limitations, a movable frame for the velocity probe was designed, which can be moved vertically up and down with the surface elevation by a disc rotor servo motor, controlled by a wave gauge. By that continuously velocities up to 3 cm below the surface could be measured. Theoretical velocities have been calculated for comparison with different simulation methods for irregular waves, based on linear wave theory.

Keywords


irregular wave; orbital velocity; near surface velocity

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