![]() ![]() Some of these processes are evident in Figure 2. Here some of the most complex transformation and attenuation processes occur, including generation of cross and longshore currents, a set-up of the mean water level and vigorous sediment transport of beach material. Once waves have broken, they enter what is termed the surf zone. Wave transformation, main concepts.Īs waves approach a shoreline, their height and wavelength are altered by the processes of refraction and shoaling before breaking on the shore. On the other hand swell waves may be characterised as fairly regular, long crested and not very steep containing a small range of low frequencies and directions.įigure 3. Thus wind waves may be characterised as irregular, short crested and steep containing a large range of frequencies and directions. The low frequency waves travel more quickly than the high frequency waves resulting in a swell sea condition as opposed to a storm sea condition. Waves of differing frequencies travel at different speeds and therefore outside the storm generation area the sea state is modified as the various frequency components separate. waves with small period) is both dissipated and transferred to lower frequencies. In the storm zone generation area high frequency wave energy (e.g. Once formed, ocean waves can travel for vast distances, spreading in area and reducing in height, but maintaining wavelength and period as shown in Figure 1. The waves are formed initially by a complex process of resonance and shearing action, in which waves of differing wave height, length, period are produced and travel in various directions. Ocean waves are mainly generated by the action of wind on water. It should be noted that this article has been abstracted from the text book “Coastal Engineering: Processes, Theory and Design Practice” 2nd edn (2012) and 3rd edn (in press), with the permission of Spon Press.įigure 1. The interested reader should consult the references provided for further details. Some results are quoted without derivation, as the derivations are often long and complex. The following sections describe some aspects of wave theory of particular application in coastal engineering. The first section provides a descriptive overview of the generation of wind waves, their characteristics, the processes which control their movement and transformation. This article explains some theories of periodic progressive waves and their interaction with shorelines and coastal structures. 7.5 Radiation Stress Components for Oblique Waves.7.1 A General Description of the Surf Zone.4.12 Combined refraction and diffraction.4.5 Shoaling and refraction of directional wave spectra.4 Wave transformation and attenuation processes.3.6 Group velocity and energy propagation.3.5 The influence of water depth on wave characteristics.3.4 Pressure variation induced by wave motion.3.3 Water particle velocities, accelerations and paths. ![]() 3.2 Numerical Solution of the Wave Dispersion Equation.3.1 Derivation of the Airy Wave equations. ![]()
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