ERDC/CHL CHETN-IV-32
June 2001
Depth (m)
20.0
18.0
16.0
14.0
12.0
10.0
8.0
6.0
4.0
2.0
0.0
-2.0
Figure 16. Detail in the area of the inlet channel
The simulation is forced with an open-ocean surface-elevation forcing and tidal potential forcing
by the M2, S2, O1, K1 and N2 constituents. Results are shown in the vicinity of the Grays Harbor
inlet channel and jetty in Figures 17 through 25. Formation of an eddy along the northwestern
tip of the above-water portion of the south jetty begins near slack tide at 1.64 days into the
simulation (Figure 17). There is a weak south to north flow across the barrier. During the
incoming tide the eddy on the north side of the jetty becomes elongated, such as at 1.66 days
(Figure 18). Cross-barrier flow from south to north is present and becomes stronger. Figures 19
and 20 are snapshots at 1.70 and 1.80 days showing eastward elongation of the northern eddy
with an increase in south to north cross-barrier flow. Initiation of the receding tide at 1.85 days
is shown in Figure 21. The eddy north of the jetty contracts and the cross-barrier flow now
reverses into a weak north to south flow. At 1.86 days into the simulation the eddy north of the
south jetty becomes smaller (Figure 22). Strong ebb flows hug both the northern and southern
edges of the inlet channel. Weak center channel flow and weak north-to-south flow across
limited portions of the south jetty are present. Strong ebb current at 1.88 days and the formation
of an eddy south of the south jetty are shown in Figure 23. The cross-barrier flow is weak. At
1.93 days the eddy to the south of the south jetty has moved away from the barrier (Figure 24).
Cross-barrier flow is extremely weak at this time. At 2.05 days, the water level is near low tide
(Figure 25). All eddies have disappeared and there is no cross-barrier flow.
The circulation patterns in the vicinity of Grays Harbor and its south jetty are complex. The
eddies that form are small scale, the inlet velocity is fast, and the advective terms contribute
significantly to the flow. If the numerical discretization and parameters are incorrectly specified,
spurious spatial oscillations can be generated. Furthermore when severe spurious modes appear,
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