Generation and Study of Wave Kinematics of Deep water and Intermediate water Ocean Waves

Abstract

In the ocean, waves are produced by variety of forces. Based on the criteria of origin, water depth and apparent shape, the ocean waves are classified as deep water, intermediate and shallow water waves. In this paper an attempt is made to simulate the ocean conditions by designing the wave generator which is housed in a wave flume of 58cm long, 44cm wide and 11cm depth. The wave generator which is used here to generate the wave is a flap type structure. The structure is hinged at both the ends of the flume and was driven by a DC motor to generate sinusoidal deep water wave with relative water depth d/L (ratio of water depth and wavelength of the generated wave) is of 2.5, which is greater than 0.5 and intermediate water wave with relative water depth in the range of 0.05<d/L<0.5.

This experimental set up is used to find the wave parameters such as wavelength, wave height, time period and wave celerity of both waves. The frequency of the generated, deep water and intermediate water waves are found to be in the range of 3Hz to 10 Hz. The values of wave parameter which were found experimentally are compared with that of values obtained by applying wave theory and are found to be closely matching. Emphasis is given to the selection of proper kinematic model and wave model based on Airys theory, which is outlined for the evaluation of wave kinematics such as velocity potential, wave particle displacement, particle velocity, particle acceleration and dynamic pressure exerted by the wave. Subsequently an attempt is made to analyse the behavior of wave kinematics for various water depths varying from SWL (Surface Water Level) till the sea bed. At the end, wave kinematic was applied in Morison equation for the evaluation of forces exerted on offshore structure and dynamic response of the structure is analysed for the same.