An instrument system to measure turbulence from an underwater habitat

Tiffin, Scott (1974) An instrument system to measure turbulence from an underwater habitat. Masters thesis, Memorial University of Newfoundland.

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Abstract

An instrument system was developed to measure oceanic turbulence from an underwater habitat in subarctic waters off the coast of Newfoundland. From a literature search of existing experimental techniques and instruments, it was seen that there was a large number of instrument systems capable of measuring turbulence, but that most were impractical without further development. After analyzing present instrument techniques, we chose DISA hot film anemometry equipment, and set up a three channel system for simultaneous three dimensional measurements. The instruments were operated from the habitat LORA 1 by SCUBA divers who also carried out Rhodamine B dye studies to delineate the turbulence. Difficulties with the two battery powered DISA anemometers subsequently reduced the system to one channel which used a DISA 55D01 anemometer with a conical probe. Two experiments were performed and preliminary analysis was presented to demonstrate the capability of the system. The data was compromised somewhat by problems associated with low mean velocities and oscillatory velocities from wave action, but spectral analysis showed the characteristic -5/3 slope and gave viscous dissipations of about 5 x 10⁻³ cm²/sec³ with turbulence intensities about 0.1. In one case, the turbulence was associated with a highly unusual oscillatory bottom current. In summary, with SCUBA divers to perform the experiments and with dye being used to delineate the water motion, DISA hot film equipment is entirely satisfactory for oceanic turbulence measurements.

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