20 
5 Model Simulations 
Circulation for No Wind and Case 1 
To determine circulation patterns, velocity vectors were plotted at each 
vertical layer (surface, mid-depth, and bottom) at every third cell. Figure 13 
shows model results at hr 5283 (lower-low water condition following the long 
ebb runout). In Figure 13, the top plots are for a no-wind condition and the 
bottom plots are for Case 1, with wind actively blowing over the harbors at 
hr 5283. The plots for no wind show a gyre in the outer harbor, set up by 
countering flows through Angel’s Gate and the West Basin (Ranges 1 and 3 
respectively, Figure 14). The gyre becomes stronger from the bottom to the 
surface. This circulation was typical of previous two-dimensional (2D) 
studies. An apparent net eastward (left to right in Figure 13) movement is 
seen in the region behind the middle breakwater. Note the relatively low 
velocities. Even during times of maximum ebb and flood flow, currents in 
the harbors are generally less than 1 fps. Only currents through the entrances 
exceed that level during strength of tide. The “active wind field" (Case 1) 
snapshots indicate a strong easterly surface flow with increasing counterflow 
(westward) in the mid-depth and bottom layers. In the western and central 
regions of the harbor adjacent to the breakwaters, bottom currents toward the 
west are predominant. 
The net bidirectional flow pattern (Case 1, surface flow toward the east 
and bottom currents toward the west) demonstrated by the 3D model is seen in 
prototype data also. Two summer months of data collected in 1987 at two 
moored current meters (CM6 and CM7, locations shown in Figure 12) 
support the model result (Figure 15). Current meter CM6S just inside 
Queen’s Gate shows strong net easterly flow on the surface. The bottom 
currents (CM6B) exhibit more diversity in direction due to their proximity to 
the harbor entrance at Queen’s Gate. Gauge CM7S shows net easterly surface 
current and CM7B shows net westerly bottom current on the eastern side of 
the harbors. 
An interesting comparison can be made between results for net circulation 
obtained with the present 3D simulation with wind (existing condition) and the 
2D, no-wind, tide-only simulations used in previous WES studies of the 
harbors (Table 2). For the 2D case, net flow is from the ocean into the 
harbors through Angel’s and Queen’s Gates and out through the east 
Chapter 5 Model Simulations 
