Wave Tank

Figure 20.10 Effect of wind speed on the air-water exchange velocity of C02 with and without contamination of the water with a mono-layer of oleyl alcohol measured in a wind-wave tank. Lines indicate linear approximation of experimental data. From Broecker et al. (1978).

Data for the experimental comparison was obtained through wave-tank experiments performed with a bottom-mounted half-cylinder so that pressure measurements could be compared directly to the numerical results (11). The obstacle was placed one-third of the tank length from a mechanical wavemaker and at the other end of the channel a sloping porous beach absorbed 95% or more of the incident wave energy. 

It was found that to within experimental error, all of the observed discrepancies could be explained by two factors. The first factor is that the model did not exactly describe the physical situation in the experiment the wave tank had a single cylinder, whereas the calculation is for a series of cylinders. The second factor was the surprising result that the roughly 5% reflected wave from the wave tank significantly affected the experimental results due to modifications in the dynamic pressure fluctuations. In this instance a detailed examination of the model and experimental results has indicated that an experimental effect thought to be small could in fact cause noticeable deviations in the data measured. 

Volatilization using Henry s law constant, ty, = 15.5 h was estimated for a model river of 1 m deep flowing at 1 m/s with a wind velocity of 3 m/s, and ty, = 14.5 h in a wind-wave tank with a 6m/s wind speed (Howard 1990). Photolysis ... 

Zhang X (1995) Capillary-gravity and capillary waves generated in a wind wave tank Observations and theories. J Fluid Mech 289 51-82... 

Wave tank study of phase velocities and damping of gravity-capillary wind waves in the presence of surface films... 

This paper presents wave tank optical measurements of phase velocities of wind waves on clean water surfaces and on water surfaces covered with organic films and measurements of film-induced water wave damping. The results confirm the assumption that the wind wave spectrum contains nonlinear cm-mm-scale harmonics bound to the dominant wind waves, giving a strong contribution to the damping of wind waves due to films. 

Experiments were carried out in the oval wind wave tank of the Institute of Applied Physics. A sketch of the experimental approach is shown in Figure 1. 

Fig. 1. Schematic diagram of the present wave tank experiment OSA = second Optical Spectrum Analyser MOSA = Multichannel ("Stroboscopic") Optical Spectrum Analyser...

The illumination system contained a transparent plastic box, installed at the bottom of the wave tank and filled with an aqueous suspension of Latex particles with a diameter of about 0.3 p - 0.4 p. A nearly parallel light beam from a line-source lamp is directed into the box. Measurements with a photo receiver have shown that the resulting light intensity, in accor-... 

Gade M, Alpers W, Ermakov SA, Huhnerfuss H, Lange PA (1998) Wind-wave tank measurements of bound and freely propagating short gravity-capillary waves. J Geophys Res 103 21697-21710... 

The wind wave tank of the University of Hamburg is 26 m long and 1 m wide. It is filled with lfesh water with a mean water depth of 0.5 m. The wind-tunnel height is 1 m, and the effective (maximum) fetch is 19 m. All measurements reported herein were performed at a fetch of 14.5 m and at wind speeds between 2 and 10 m s"1 generated by a radial blower. In the measurement and rain area, the metallic plates of the tank s roof were removed and, on the leeward side, replaced by Styrofoam panels to ensure the unattenuated transmission of the microwaves (Figure 2). At the windward side of the rain area plates of microwave absorbing material were vertically mounted in the direction of the specular-reflected radar beams. 

Fig. 2. Schematic side view of the wind-wave tank. 1 blower, 2 honeycomb, 3 wave flap, 4 anemometer, 5 rain generator, 6 radar absorber plates, 7 wire, 8 laser, 9 laser optics, 10 X band antennae, 11 beach and overflow baffle, 12 diffusor, 13 slick deployment.

Measurements of surfactant concentrations on travelling capillary waves is complicated by the rapid decay rate of these waves, necessitating measurements close to the source of wave generation. To avoid this complication, we utilized a field of standing capillary waves. The wave tank was a circular (6.99 cm, inner diameter) glass vessel. The inner wall was coated with paraffin to avoid loss of the surfactant to the tank side walls. Triply distilled water was used as the substrate. The tank was overflowed to clean the surface prior to spreading the insoluble hemicyanine surfactant mono-layer at a surface concentration of 0.288 pg cm"2. Hemicyanine, 4-[4-(dimethylamino)styrl]-l-docosyl-pyridinium bromide, is a stilbazolium dye molecule to which is attached on one end a saturated twenty two car-... 

In order to complement the results of the radar backscatter measurements on the open sea, laboratory measurements of the wave amplitude and slope and of the radar backscatter at X- and Ka-band were carried out in a wind-wave tank with mechanically generated gravity waves as well as with wind-generated waves on a slick-free and a slick-covered water surface. In this paper, we concentrate on the results of the radar measurements with wind-generated waves. For a full description of the obtained results the reader is referred to Gade et al. (1998c). 

These results obtained from a slick-covered water surface are of great importance for the interpretation of measured reductions of the radar back-scattering by oceanic surface films (see the preceding sections). However, we also note that results obtained from wind-wave tank experiments can-... 

The results from the wind-wave tank measurements show that at X- and Ka-band the radar backscattering from a slick-free water surface is caused by bound as well as by free propagating ripples. In the presence of a monomolecular surface film at certain wind speeds only bound or only free propagating ripples are responsible for the backscattering at X-band, which can explain higher measured damping ratios. 

L. E. Harris, www.artificialreefs.org/ScientificReports/research.htm Submerged Reef Structures for Habitat Enhancement and Shoreline Erosion Abatement FIT Wave Tank and Stability Analysis of Reef Balls, http //www.advancedcoastaltechno-logy.com/science/DrHarris Wavereduction.htm. 

In this chapter, a 2D nonlinear wave-structure interaction problem is formulated using a potential-based fully nonlinear Numerical Wave Tank (NWT). Figure 24.8 shows the definition sketch for a vertical cylinder assumed frozen at an instant in wave. The theory is based (closely following the work of Kim and Koo ) on mode-decomposition method, and MEL material-node time marching scheme, and uses the boundary element method (BEM). 

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