Wave Tanks

Nomenclature

Chapter 4 Chapter 4 Procedures

4.1 Wave Tanks and Wave Generation System

4.1.1 Wave Tanks

Chapter 4

English units. The wave tank was constructed with glass sidewalls throughout and a painted structural steel bottom. The glass wall of each section is l.52 m long, 63.50 em high and l.27 cm thick. The bottom is leveled carefully with the deviation from the horizontal surface less than ±2.5 nun. The joints along the edges of the glass and t he bottom were sealed with silicone caulking to eliminate leakage. Stainless steel rails 3.1)1 em in diameter are mOlmted along the top edge of the wave tank and are leveled to within ±O.3 mm. ),Iovable instrument carriages are designed for these rails.

A steel scale is mounted along the top edge of the tank to provide all accurate measure of distance. An aluminum ramp was installed at one end of the fiume joined to the constant depth region with the toe of the slope 17.30 m from the wave generator. The beach was 14.15 ^III long constructed of 5 panels of 0.64 em thick anodized aluminum plate. A frame was constructed of aluminum angles ( 2.5 in x 2.5 in) to support the beach. with the material anodized before assembling. Each plate was fixed to the aluminum frame by countersunk screws, and the gap above the heads of the screws was filled with wax to guarantee the smoothness of the slope surface. The edges of the plates were machined with a groove on one plate and a matching protrusion on the other resulting in a "tongue and groove" joint. This provided a smooth surface across the joints and a rigid plane beach face to be mounted to the frame; where there was a small gap between plates, wax was used. The frame consisted of five modules, each 2.83 m long. Each module was supported on four leveling legs with screws whose length can be adjusted according to the beach slope. (The toe section only had two adjustable legs.) A detail of a leveling screw is shown in Figure 4.3.

The aluminum frame was installed in the tank by first placing one frame module on the tank bottom without the beach plate. Then the slope of the frame module was adjusted to the desired angle by changing the four leveling screws at both ends. This process was repeated until all the frame modules were set in place and adjusted to the same slope. This method allowed each frame module to be leveled independently

without adjusting the adjacent module. The leveling screws were locked in place. The aluminulll plates were attached to the frame and sealed in place with silicone. For the breaking solitary run-up experiments the beach was set at the slope of 1 vertical to 15 horizontal with a deviation from a plane surface of less than ±1 mm. This slope \vas chosen so that a range of offshore wave heights could be used with the wave breaking either 011 run-up or run-down. (The ramp is also shown in Figure 4.2.) A photograph of the wave tank and beach is presented in Figure 4.4. To balance the hydrostatic pressure acting on the sloping plate. the wave tank section behind the plate was filled with water so that the still water level was the same as that in the test section.

The maximum run-up of breaking solitary waves for water depths ho

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30.48 em were measured in the CERC wave tank. The CERC wave tank is 45.7 m long, Cl.9 III

wide and 0.9 m deep. A sketch is presented in Figure 4.5 showing the wave tank and the setup of the experiments. The beach used in the CERC tank was constructed of painted plywood and the slope was set at 1:15. Thus. the experimental data from this tank could be compared to that from Caltech 'West Tank (CWT). The plywood beach was sealed to the tank walls and the tank bottom with silicone.

Non-breaking solitary wave run-up experiments were conducted in the relatively short wave tank at Caltech (CST). The wave tank is 15.25 m long. 39.6 em wide, and 61 em deep and consists of 5 identical sections that are each the same as those in the C~TT. The plane beach used was 2.83 m long and was composed of one beach module used in the c\~rT. A small wedge made of lucitc was machined and installed at the toe of the slope to eliminate the gap hetween the wave tank bottom and the beach. The beach was installed with the toe of the slope 12.35 m from the wave generator and the slope of the beach was adjustable also; for these experiments it was set at 1:2.08 with a deviation from a plane surface of less than ±1 lIUll. This slope ,vas chosen so that a reasonably large offshore wave height could be llsed without

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114" I/Z'GLASS PANELS Figure 4.2: Schematic sketch of one section of the Caltech west tallk (CYVT, after Synolakis (1986))

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Slope Frame

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Adjustable Screw 3

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Figure 4.3: Schematic sketch of the adjustable legs used to support the beach frame ofGWT

the wave breaking either on run-up or run-down. A photograph of the non-breaking solitary wave run-up experimental setnp is shown in Figure 4.G.

Figure 4.4: A photograph of the ramp and the Caltech west tank (GWT)