Author(s): Martin Schletterer; Hugo Gotsch; Effrey A. Tuhtan; Juan Fran Fuentes-Perez; Maarja Kruusmaa
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Keywords: Pressure; Aquatic ecosystem; Turbulence; ADCP; Barotraum
Abstract: Natural flows are a complex amalgamation of velocity, vorticity and pressure. Water rapidly attenuates light and electromagnetic fields but due to its high density provides an excellent medium for the transmission of pressure field fluctuations, both hydrodynamic (mechanical fluid motion) and hydroacoustic (energy transmission). Aquatic vertebrates such as fish use a variety of pressure sensitive systems including their inner ear, lateral line and in some species their swim bladder to localize, communicate and create hydrodynamic images of the aquatic environment. Inspired by the ubiquitous use of pressure-based systems of fishes, we have developed two pressure sensing systems which can aid in studies of the aquatic environment. First it is shown how a differential hydrodynamic pitot system can provide estimates of spatially distributed turbulence in conjunction with ADCP measurements in front of a hydropower intake. Second, preliminary results are provided from a prototype barotrauma detection system for downstream passage through hydropower turbines using neutrally-buoyant pressure sensors. Our objective is to show that pressure sensors can offer much more information than just the water depth, and are an excellent source of new data by collecting hydrodynamic metrics in aquatic environments. Future applications in pressure sensing devices for aquatic ecosystems can benefit from the new information won using the high-frequency measurements in the 100-500 Hz range, which corresponds to the hydrodynamic bandwidth sensed by most aquatic vertebrates. Thus pressure-based measurements will allow researchers to investigate ecologically-relevant flows from a physical point of view closer to that of the indicator organism.
Year: 2017