ERDC/CHL CETN-IV-27
September 2000
Magnitude Difference
0.80
0.74
0.67
N
0.61
0.54
0.48
0.42
0.35
0.29
0.22
0.16
0.10
0.03
-0.03
-0.10
-0.16
-0.22
-0.29
-0.35
-0.42
-0.48
-0.54
-0.61
-0.67
-0.74
-0.80
Figure 11. Velocity vector difference plot overlaid on contours of velocity magnitude difference (units in
ft/s) to evaluate proposed reorientation of the spur jetty (To convert feet per second to meters per
second, multiply by 0.3048)
Figure 11 shows the effectiveness of the alternative during the same flow conditions shown in
previous alternatives. The plot contains contours of velocity magnitude difference overlaid with
a plot of velocity vector difference. The plot was constructed by first running the existing
baseline condition and the proposed alternative condition. To create the contours, the baseline
output was converted to scatterpoint data. This data set was then interpolated onto the alternative
condition mesh. Finally, the baseline velocity magnitude scalar data set was subtracted from the
alternative velocity magnitude data set via the SMS data calculator to create a velocity-difference
data set. The contours show this velocity difference. Positive values indicate increases in
velocity associated with the alternative, and negative values indicate decreases. The vector data
set was created by first deconstructing the baseline vector data set into its x- and y-components.
These scalar data sets were then converted into scatterpoint data and interpolated onto the
alternative mesh. The alternative vector data set was also deconstructed into its x- and y-
components. Next, two scalar data sets of the difference between the alternative and the baseline
x- and y-velocity components were created via the SMS data calculator. Finally, a vector data
set was constructed from the two difference data sets. The result is the subtraction of the
baseline vector from the alternative vector. The vector length is proportional to the magnitude of
change.
The contours reveal areas of increase and decrease in velocity magnitude. The alternative
appears to reduce the velocity magnitude near the shoreline (indicated by the blue contours).
However, a marked increase occurs in the velocity just west of the east jetty (indicated by red
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