Experimental Verification of Wave Height Predictions for Shallow Wave Basin in a Top Hinged Flap type wave Generator

Abstract

This paper describes an attempt to verify experimentally relative wave heights generated by flap-type wave
generator against theory. The experiments are performed using Random Sea Wave Generators at CWPRS (Central
Water Power Research Station), Pune. The experiments have been conducted in a shallow wave basin, and the
wave-height envelope is measured with capacitance wave height recorders placed at various locations in wave
basin. The ratio of the height of wave generated by displacement type wave generators in shallow water to the
stroke of the flap is approximated as H/S= kd. ‘S’ is the stroke of the wave generator, ‘k’ is the wave number given
by the small-amplitude theory, ‘d’ is depth of water in wave basin and H is the height of wave measured
perpendicular to S. Agreement of this relation with the hydrodynamic theory for flap-type wave generators over the
range of relative depths usually used in coastal engineering experiments are studied. Wave height-stroke transfer
functions that are used to generate the desired wave height at selected period as the volume of the displaced fluid
during a single stoke is directly proportional to the volume under the crest of the generated wave.