EM 1110-2-1100 (Part II)
30 Apr 02
sampled periodically at several points in the harbor for a period of several tidal cycles. Initial and subsequent
dye concentrations (see Equation II-7-20) can be measured in situ by a standard fluorometer. The dye
Rhodamine WT has been used in a number of harbor flushing studies (see Callaway (1981) and Schwartz and
Imberger (1988)).
II-7-7. Vessel Interactions
a. Vessel-generated waves.
(1) As a vessel travels across the water surface, a variable pressure distribution develops along the vessel
hull. The pressure rises at the bow and stern and drops along the midsection. These pressure gradients, in
turn, generate a set of waves that propagate out from the vessel bow and another generally lower set of waves
that propagate out from the vessel stern. The heights of the resulting waves depend on the vessel speed, the
bow and stern geometry, and the amount of clearance between the vessel hull and channel bottom and sides.
The period and direction of the resulting waves depend only on the vessel speed and the water depth. For
a detailed discussion of the vessel wave-generating process and the resulting wave characteristics, see Robb
(1952), Sorensen (1973a, 1973b), and Newman (1978).
(2) The pattern of wave crests generated at the bow of a vessel that is moving at a constant speed over
deep water is depicted in Figure II-7-40. There are symmetrical sets of diverging waves that move obliquely
out from the vessel's sailing line and a set of transverse waves that propagate along the sailing line. The
transverse and diverging waves meet along the cusp locus lines that form an angle of 19E28' with the sailing
line. The largest wave heights are found where the transverse and diverging waves meet. If the speed of the
vessel is increased, this wave crest pattern retains the same geometric form, but expands in size as the
individual wave lengths (and periods) increase.
Figure II-7-40. Wave crest pattern generated at a vessel bow moving over deep
water
(3) The fixed pattern of wave crests requires that individual wave celerities C be related to the vessel
speed Vs by
C ' Vs cos θ
(II-7-21)
II-7-54
Harbor Hydrodynamics
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