Flow-Noise and Turbulence in Two Tidal Channels

Journal Article

Title: Flow-Noise and Turbulence in Two Tidal Channels
Publication Date:
February 10, 2014
Journal: Journal of the Acoustical Society of America
Volume: 135
Pages: 1764-1774
Publisher: Acoustical Society of America
Stressor:
Technology Type:

Document Access

Website: External Link

Citation

Bassett, C.; Thomson, J.; Dahl, P.; Polagye, B. (2014). Flow-Noise and Turbulence in Two Tidal Channels. Journal of the Acoustical Society of America, 135, 1764-1774.
Abstract: 

Flow-noise resulting from oceanic turbulence and interactions with pressure-sensitive transducers can interfere with ambient noise measurements. This noise source is particularly important in low-frequency measurements (f < 100 Hz) and in highly turbulent environments such as tidal channels. This work presents measurements made in the Chacao Channel, Chile, and in Admiralty Inlet, Puget Sound, WA. In both environments, peak currents exceed 3 m/s and pressure spectral densities attributed to flow-noise are observed at frequencies up to 500 Hz. At 20 Hz, flow-noise exceeds mean slack noise levels by more than 50 dB. Two semi-empirical flow-noise models are developed and applied to predict flow-noise at frequencies from 20 to 500 Hz using measurements of current velocity and turbulence. The first model directly applies mean velocity and turbulence spectra while the second model relies on scaling arguments that relate turbulent dissipation to the mean velocity. Both models, based on prior formulations for infrasonic (f  < 20 Hz) flow-noise, agree well with observations in Chacao Channel. In Admiralty Inlet, good agreement is shown only with the model that applies mean velocity and turbulence spectra, as the measured turbulence violates the scaling assumption in the second model.

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