G

where *V *= average horizontal velocity at a node

(5) For example, when *H *= 1 ft, *T*1 = 200 sec, and *d *= 30 ft, the maximum horizontal velocity and particle

excursion are *V*max = 0.5 ft/sec and *X *= 33 ft.

(6) The resonant response of the simple rectangular harbor, presented by Ippen and Goda (1963) in terms

of the amplification factor *A *(assuming no viscous dissipation) and the relative harbor length *k*R, where *k *=

is traditionally defined as the ratio of wave height along the back wall of the harbor to standing wave height

along a straight coastline (which is twice the incident wave height). The response curve for a long, narrow

harbor is given in Figure II-7-30. The left portion of the curve resembles that for the mechanical analogy in

Figure II-7-26. Resonant peaks for higher order modes are also shown. The three curves correspond to a

fully open harbor and two partially open harbors with different degrees of closure. The *k*R value at resonance

decreases as the relative opening width decreases. It is bounded by the value for a closed basin, also shown

in the figure. Amplification factors for the inviscid model are upper bounds on those experienced in a real

harbor. Because amplification factor decreases at each successive higher order mode, simple analysis

methods often focus only on the lowest order modes.

(7) Practical guidance for assessing the strength and period of the first two resonant modes in a partially

enclosed rectangular harbor with a symmetric entrance is given in Figure II-7-31. A wide range of relative

harbor widths (aspect ratios, *b/*R) and relative entrance widths (*d/b*) is represented. The *k*R values can be

converted to resonant periods by

II-7-38

Harbor Hydrodynamics

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