ERDC/CHL CHETN-I-66
June 2002
2.5
Distribution 1
Distribution 2
2
Linear Interpolation
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Figure 2. Linear interpolation of directional shapes
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Distribution 1
Distribution 2
Interpolated Output
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Direction (deg)
Figure 3. Result of morphic interpolation (compare with linear result in Figure 1)
The morphic technique is applicable only for single peaked wave spectra because the entire
distribution is shifted based on a single peak direction. This technique is appropriate for climatic
wave transformation studies where a parametric spectral shape is applied based on wave parameters.
NESTING EXAMPLE: To test the nesting scheme, three idealized cases were developed. The
cases consist of a plane beach with a slope of 0.004, offshore depth of 16 m, and three different sized
elliptical shoals with the long axes parallel to the shoreline. The shoals were centered on the 8-m
depth contour, and the depth at the top of the shoal was 4 m. Shoal dimensions are given in Table 1.
The large shoal bathymetry is illustrated in Figure 4. The domains were modeled with three grids
(250-m coarse grid, 25-m fine grid, and 25-m nested grid, with the nest occurring at the peak of the
shoal). Nested grid simulations were run with both linear and morphic interpolation, with each
simulation consisting of 24 input wave conditions. The peak periods ranged from 6 to 18 sec, the
peak directions ranged from 0 to 45 deg, and the wave heights were 2 m. The TMA spectral shape
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