The Impact of Turbulent Fluctuations on Light Propagation in a Controlled Environment
NAVAL RESEARCH LAB STENNIS DETACHMENT STENNIS SPACE CENTER MS OCEANOGRAPHY DIV
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Underwater temperature and salinity microstructure can lead to localized changes in the index of refraction and can be a limiting factor in oceanic environments. This optical turbulence can affect electro-optical EG signal transmissions that impact various applications, from diver visibility to active and passive remote sensing. To quantify the scope of the impacts from turbulent lows on EG signal transmission, and to examine and mitigate turbulence effects, we perform experiments in a controlled turbulence environment allowing the variation of turbulence intensity. This controlled turbulence setup is implemented at the Naval Research Laboratory Stennis Space Center NRLSSC. Convective turbulence is generated in a classical Rayleigh-Benard tank and the turbulent flow is quantified using a state-of-the-art suite of sensors that includes high-resolution Acoustic Doppler Velocimeter profilers and fast thermistor probes. The measurements are complemented by very high-resolution non-hydrostatic numerical simulations. These computational fluid dynamics simulations allow for a more complete characterization of the convective How in the laboratory tank than would be provided by measurements alone. Optical image degradation in the tank is assessed in relation to turbulence intensity The unique approach of integrating optical techniques, turbulence measurements and numerical simulations helps advance our understanding of how to mitigate the effects of turbulence impacts on underwater optical signal transmission, as well as of the use of optical techniques to probe oceanic processes.
- Fluid Mechanics