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The applicability of a k-e turbulence model for low-Reynolds numbers to oscillatory boundary layers is examined. Through several numerical computations, characteristics of the mean velocity and tur...

Two-dimensional laboratory experiments were performed to investigate the sediment transport due to waves on a smooth fixed sloping beach. Polystyrene particles and glass balls were used as tracers ...

In order to clarify the non-linear effect of the width between two adjacent orthogonals on the wave height change due to refraction, the equations of transformation for finite amplitude waves inclu...

In order to clarify the water particle velocity field of breaking waves on beaches, experiments were carried out for three kinds of beach slopes (1/10, 1/20 and 1/30). Neutrally buoyant particles were used as tracers to measure the velocities with a 16 mm high speed cinecamera. Since photographs of the wave profile near breaking were also taken in the same films, the change of the wave profile near breaking was also examined. It was found that vertical distributions of horizontal water particle velocities at the crest and trough phases of breaking waves on beaches cannot be explained by the finite amplitude wave theories for uniform depth. Then, they were discussed in comparison with the breaker types. As a result, it was shown that the dimensionless vertical distribution of horizontal water particle velocity at the crest phase of breaking waves is determined by the combination of the beach slope and the deep-water wave steepness.

This paper has examined the change of wave grouping of storm waves during wave growth and decay by analyzing the field wave data observed off Gobo Coast in Wakayama Prefecture and at Lake Biwa in Shiga Prefecture (Japan) with some parameters to describe the magnitude of wave groups. For the mean lengths of runs and total runs of wave heights, the comparison of the observed results with the theoretical ones by Kimura (1980) has been done. Besides, the effect of shallow water on wave grouping has been discussed.The main results are as follows: (1) To describe the magnitude of wave groups, at least two parameters are needed; one is the magnitude of the sequence of high waves in a time series, and the other is the magnitude of the variation of wave energy or wave height around the mean value. (2) Concerning the wave data observed at Gobo, wave grouping was pronounced in the main stage of storms where three parameters of the correlation coefficient of successive wave heights, the mean length of runs an...

In forecasting ocean waves in shallow water, the value of the bottom friction factor must be known for the calculation of wave energy loss due to bottom friction.In this paper the attenuation data ...

As a breaking limit of progressive waves, many conditions have been proposed. One of them is that the water particle velocity at the wave crest is equal to the wave celerity.To examine this condition experimentally, the wave profile and the horizontal water particle velocity at the water surface near the crest of breaking waves were measured. These waves progress and break on a very gentle slope beach (1/200), which may be regarded as horizontal bottom.Experimental results of the wave profile and the horizontal water particle velocity at the water surface near the crest of breaking waves are presented and compared with theoretical values, and the breaking condition of progressive waves is examined experimentally.

SynopsisSandy beaches are defensive zones created by nature, protecting the land against aggressive oceanic forces. They are very flexible and their configulations are varying daily, seasonally and annually, depending on many factors, such as wave characteristics, beach materials, shore structures and the others. The investigation of beach erosion is one of the most important and difficult subjects in coastal engineering.In this paper, a method for investigating the mechanism of beach erosion is presented, concerning the investigation practice of beach erosion along the north coast of the Akashi Strait, and the author's opinion of the following three subjects to be investigated is described:(a) Distribution of sand drift along the coast,(b) Distribution of sand drift along the beach profile, and(c) General characteristics of sand drift, suCh-as the type of sediment transport, the direction of drift and the others.

Is is very difficult for engineers to deal with the cnoidal wave theory for practical application, since this theory contains the Jacobian elliptic functions, their modulus k, and the complete elliptic integrals of the first and second kinds, K and E respectively. This paper firstly proposes formulae for various wave characteristics of new waves named "hyperbolic waves", which are derived from the cnoidal wave theory under the condition that k = 1 and E = 1 but K is not infinite and are a function of T/g/h and H/h, so that cnoidal waves can be approximately expressed as hyperbolic waves by primary functions only, in which T is the wave period, h the water depth and H the wave height. Secondly, as an application of the hyperbolic wave theory, the present paper deals with wave shoaling, that is, changes in the wave height, the wave crest height above still water level, and the wave velocity, when the waves proceed into shallow water from deep water.