Visser

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.

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
Simulation Duration	3 hr	3 hr	none
Ramp Duration	3 hr	3 hr	none
Steering Interval	0.25 hr	0.25 hr	none

Calibration Parameters	Case 4	Case 7	Default
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 7

References

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

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Test_Cases