Viscous dissipation of monochromatic waves in still water of finite constant depth in a channel of finite width

Viscous dissipation of monochromatic waves in still water of finite constant depth in a channel of finite width

Suastika, I.K.

Civil Engineering and Geosciences

Hydraulic Engineering

1999-01-01

Energy dissipation of water waves propagating in a smooth-walled channel of finite water depth and finite width is mainly due to viscous effects. Providing that the wave length is sufficiently large compared to the water depth and a finite channel width, wave energy is principally dissipated in the boundary layers on the bed and on the walls. Hunt [1952] studied the attenuation of periodic water waves travelling in shallow water in a channel of finite width. In the present study we investigate experimentally the wave attenuation of monochromatic waves travelling in still water of finite constant depth in a channel of finite width. In the experiments, we measured the water surface elevation at a number of locations along the flume. First, Fourier analysis is performed to the surface elevation data, in which the surface elevation is represented as a sum of many harmonic components. This analysis is performed to the surface elevation data obtained at each station, resulting in discrete values of wave amplitudes and phase shifts as function of wave travel distance. Next, the values of wave amplitudes and phase shifts so obtained are modelled by using a wave attenuation model in order to estimate the damping modulus K. Finally, the damping modulus K so determined is compared with that calculated using the formulation of Hunt. CONCLUSION The damping modulus representing the wave attenuation determined from the laboratory measurements of Auke - method gives on average slightly higher values of the damping modulus than the values from the theory by Hunt.

damping modules
viscous dissipation
monochromatic waves
still water
energy dissipation
Auke-method

http://resolver.tudelft.nl/uuid:4960775d-1b9d-4da9-b29a-69e96cd0005c

TU Delft, Department of Hydraulic Engineering

Institutional Repository

report

(c) 1999 TU Delft, Department of Hydraulic Engineering