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

Computational Grid

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. A summary of some of the simulation settings used for both experiment cases are shown in the table below.

Settings	Value
Solver	Implicit
Time Step	60 sec
Wetting and Drying Depth	0.001 m
Simulation Duration	3 hr
Ramp Duration	3 hr
Steering Interval	0.25 hr

Results

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

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