Nearshore Refraction Simulation 
Wave transformation model 
46. An estimation of wave transformation from the nominal 18.29-m 
(60 ft) depth to the nominal 3-m depth (10 ft) along the coast was made by 
application of the Regional Coastal Processes Wave Model, RCPWAVE (Ebersole, 
Prater, and Cialone 1986). RCPWAVE was specifically designed for use in 
projects with large spatial extent, such as in the present case. This model 
is superior to classical wave ray refraction procedures in that energy propa- 
gation along wave crests due to irregular bathymetry is accounted for in addi- 
tion to energy propagation in the direction of ray travel. The model is also 
more efficient than wave ray models since the governing equations are solved 
directly on a user-specified depth grid in the horizontal plane (by an itera- 
tive finite-difference solution scheme) rather than by ray shooting and inter- 
polation to the grid. 
47. Basic assumptions used in RCPWAVE are: 
Mild bottom slopes 
Linear, monochromatic, and irrotational waves 
Negligible wave reflection 
1a 10 Io |p 
Negligible energy losses due to bottom friction or wave 
breaking outside the surf zone 
48, These assumptions are common to most numerical models used for 
engineering application. Results from the model are expected to be adequate 
for estimating longshore sand transport rates. 
49. Model Grid and Boundary Conditions. The main model grid (Figure 9) 
is rectangular with a mesh of 106 cells across-shore (positive x-axis directed 
offshore) and 240 cells alongshore (positive y-axis directed north). The cell 
spacing alongshore was set at 150 m; the cross-shore cell spacing was 75 m. 
This grid spacing is fine-meshed for wide-area modeling, but it was considered 
the minimum necessary to resolve any systematic irregularities in the breaking 
wave pattern that might be induced by unusual bottom features in the area. 
50. The main grid covers the coast from Sandy Hook navigation channel 
on the north to a point just beyond Lake Como. Across-shore, the grid extends 
from inland of the present shoreline seaward to approximately the 20-m con- 
tour. The grid was extended well outside the Sea Bright to Ocean Township 
project area to eliminate possible contamination from the lateral boundary 
conditions. 
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