Visser: Difference between revisions

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| Roller efficiency coefficient || 0.8 || - || 1.0
| Roller efficiency coefficient || 0.8 || - || 1.0
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| Turbulence Model || Subgrid || Subgrid || Subgrid
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| Eddy viscosity base value || 1.e-6 || 1.e-6 || 1.e-6
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| Eddy viscosity bottom coefficient || 0.06 || 0.06 || 0.06
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| Eddy viscosity horizontal coefficient || 0.2 || 0.2 || 0.2
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| Eddy viscosity horizontal coefficient || 0.2 || 0.2 || 0.2
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| Eddy viscosity wave coefficient || 0.1 || 0.1 || 0.1
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| Eddy viscosity wave breaking coefficient || 0.05 || 0.05 || 0.05
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Revision as of 14:31, 13 October 2010

Experimental Setup

In 1991, Visser conducted eight laboratory experiments of monochromatic wave on a planar beach and collected measurements on waves, currents and water levels. The bathymetry consisted of a 1:10 slope for the first 1-m seaward distance, a 1:20 slope for the next 5-m distance, followed by a 5.9 m distance of flat bottom to the wave generator. Both experiments had incident wave heights of 0.078 m, peak periods of 1.02 sec and an incident wave angle of 15.4°. Experiment 4 was run over a concrete bed and experiment 7 was run of a thin 0.005-0.01 m layer of gravel grouted on the concrete floor.

Wave Parameter Case 4 Case 7
Height 0.08 m 0.08 m
Period 1.02 m 1.02 m
Incident Angle 15.4° 15.4°

Model Setup

The computational grid (shown in Figure 1) consists of 84 rows and 147 columns with a constant grid resolution in the longshore direction of 0.15 and a variable grid resolution between 0.04 and 0.15 m in the cross-shore direction. A zero water level was forced at the offshore boundary.

Computation Grid
Computational Grid


Results

The figures below show a comparison between measured and computed bed elevations.

Settings Case 4 Case 7 Default
Time Step 60 sec 60 sec none
Steering Interval 0.25 hr 0.25 hr none
Wave-current bottom friction Fredsoe 1984 Fredsoe 1984 Quadratic
Manning's n 0.0115 0.018 0.025
Roller On Off Off
Roller dissipation coefficient 0.1 - 0.1
Roller efficiency coefficient 0.8 - 1.0
Case 4
Case 4
Case 7
Case 7


References

  • Visser, R. J. (1991) “Laboratory measurements of uniform longshore currents”. Coastal Engineering, 15, 563-593.

Test_Cases