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Experiments to determine the length, height and steepness of bed forms generated by wave action have been conducted in a laboratory wave flume and an oscillating water tunnel. The effects of a wide range of oscillatory flows were examined on polystyrene (specific gravity 1.05, diameter 1.54 mms), bakelite (specific gravity 1.60, diameter 0.52 mms), bakelite (specific gravity 1.51, diameter 0.67 mms) and sand (specific gravity 2.68, diameter 0.36 mms). From the results of the experiments design curves were plotted which make it possible to predict the length and height of bed form that will develop on any specified sediment bed for given conditions of fluid oscillation.

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The forces and overturning moments exerted by waves on a vertical circular caisson, extending from the ocean bottom through the water surface, have been measured for a range of wave heights and periods. The wave loads were measured on a 1:60 scale model of a rigid circular caisson, 60 ft (18.3 m) in diameter, in a water depth of 145 ft (44.2 m). A digital computer was used for the acquisition, processing, plotting, and storage of data. Experiments were conducted for a range of conditions described by water depth on incident wavelength d/L from 0.179 to 0.786, wave steepness H/L up to 0.076, and caisson diameter on incident wavelength D/L from 0.074 to 0.325. The experimental results were compared with values computed by the diffraction theory of MacCamy and Fuchs and showed that the theory is suitable for use over the range of conditions described above.

Large-scale laboratory tests of the evolution of bedforms in sand beds, under directional irregular waves, carried out at the National Research Council Canada, are described. Preliminary observations indicate that the directionality of the waves is not an important factor; bedforms remained largely two-dimensional under all but transitional conditions. Incident wave height and period, probably combined as a wave orbital amplitude near the bed, seems to be the most important factor in determining bedform dimensions, followed by the D,, sand size on the bed. Sand gradation may be unimportant.Le presente expose decrit des essais a une echelle relativement grande, entrepris au laboratoire du Conseil national de recherches du Canada, sur la configuration des lits de sable sous I'action des vagues irregulieres et multidirectionnelles. Des observations preliminaires indiquent que la directionalite des vagues n'est pas importante : la configuration du fond est restCe presque bidimensionelle, sauf sous les conditions de transition. Le parametre le plus important pour la prediction des dimensions de la configuration du fond semble Etre l'amplitude orbitale des vagues pres du fond, exprimee ici en terme de la hauteur et de la periode des vagues, suivie par la granulometrie, D,,, du fond. La gradation du sable est peut-Etre moins importante.

The forces and overturning moments exerted by waves on large vertical square-section caissons have been measured in the laboratory. Each model caisson extended from the bottom of a wave flume through the water surface and was oriented either with one side perpendicular to the direction of wave propagation or turned through an angle of forty-five degrees to this position. For a given orientation, each model was tested for a range of wave heights (up to the point of breaking) for various wave periods and water depths. A digital computer was used for the acquisition, processing, plotting and storage of the experimental data. In addition to the experimental work, an approximate theoretical method is presented which allows the wave loadings on a square caisson to be estimated by means of a simple desk calculation. The experimental data shows that this simple method of calculation is reasonably accurate over a wide range of wave conditions and caisson sizes.