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Max Hammond Wavetank
SRI’s Max Hammond Wavetank has been used extensively for studying the potential detectability of submerged tethered objects and wideband shallow water wave evolution. New uses include the design of waterborne micro-algae photobioreactors for biofuel production. Inquiries on collaboration and research on other applications are invited.
The wavetank is 20 m long, 1.3 m wide, and 1.5 m high. For optimum optical access, it is built with glass walls carried on a steel frame. Waves in the tank are created by a sector-carrier-designed shallow water wavemaker built by Edinburgh Designs.
The wavemaker is capable of producing arbitrary wave profiles with a dominant wave frequency between 0.2 and 1.5 Hz. Data can be obtained using several different measuring systems, including capacitative wave height gauges, particle image velocimetry (PIV), and Ku-band radar.
Research results include:
- Detectability of submerged tethered objects
Previous research has shown the presence of a number of different types of surface signatures due to hydrodynamic phenomena associated with the presence of shallowly submerged tethered objects. SRI’s research set bounds on the potential detectability of these features using a simple microwave radar setup. Our results showed that for monochromatic incident wave spectra, the strength of radar returns falls off dramatically as the sphere submergence increases. This can be directly traced to the weakening of different surface signature mechanisms. For Joint North Sea Wave Project (JONSWAP) incident wave spectra, the strength of the radar return falls off gradually as the sphere submergence increases until a critical value is reached. These results showed that mine detection by radar is certainly possible over a range of mine submergences.
- Wideband shallow water wave evolution
Previous research has not focused on the creation or evolution of turbulent bores created by breaking water waves, nor on the evolution of such waves over realistic bars on the ocean bottom. SRI’s research delved into both of these topics in great detail. Our results showed that the self-similar nature of turbulent bores postulated by earlier researchers was indeed correct, although some modification was needed in the scalings necessary to non-dimensionalize the amplitude and velocity of such bores. The evolution of waves over bars on the ocean bottom was shown to be highly nonlinear and to have important implications for the evolution of the waves beyond such bars.
The wavetank is named in memory of Carl "Max" Hammond, an SRI engineer who helped build and operate it.