(f) Bowers and Welsby (1982) conducted a physical model study of wave diffraction through a gap

between two breakwaters whose axes are angled (rather than being collinear, i.e. 180 deg). Breakwater

interior angles of 90 deg and 120 deg were employed. As would be expected, angling the breakwaters

increased the heights behind the breakwater compared with the results for collinear breakwaters. But the

increases were relatively small - up to 15 percent for 120-deg interior angles and up to 20 percent for 90-deg

interior angles, when gap widths were in excess of half a wavelength.

(g) Memos (1976, 1980a, 1980b, 1980c) developed an approximate analytical solution for diffraction

through a gap formed at the intersection of two breakwaters having axes that are not collinear but intersect

at an angle. The point of intersection of the breakwater axes coincides with the tip of one of the breakwaters.

Memos' solution can be developed for various angles of wave approach.

(1) The preceding discussion of wave diffraction was concerned with monochromatic waves. The effects

of wave diffraction on an individual wave depend on the incident wave frequency and direction. Thus, each

component of a directional wave spectrum will be affected differently by wave diffraction and have a

different *K*N value at a particular point in the lee of a breakwater.

Harbor Hydrodynamics

II-7-9

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