Acoustic imaging in application to reconstruction of rough rigid surface with airborne ultrasound waves

Krynkin, Anton; Dolcetti, Giulio; Hunting, S.

doi:10.1063/1.4974842

Cited by 9 publications

(2 citation statements)

References 21 publications

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“…If this potential can be realized, passive optical remote sensing could complement other methods for noncontact flow measurement. Current approaches include large‐scale particle image velocimetry (PIV) using foam or other debris captured by video [e.g., Muste et al , ; Lewis and Rhoads , ; Tauro et al , ] or thermal signatures [e.g., Puleo et al , ; Dugan et al , ], various forms of radar [e.g., Costa et al , ; Fulton and Ostrowski , ], and airborne acoustic measurements of surface roughness [ Krynkin et al , ]. The ability to estimate velocities from optical, thermal, radar, or acoustic data could enable remote measurement of river discharge, provided depth information also can be obtained via remote sensing or some other independent means; this is an important and long‐standing objective in the hydrologic sciences.…”

Section: Discussionmentioning

confidence: 99%

A framework for modeling connections between hydraulics, water surface roughness, and surface reflectance in open channel flows

2017

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This paper introduces a framework for examining connections between the flow field, the texture of the air‐water interface, and the reflectance of the water surface and thus evaluating the potential to infer hydraulic information from remotely sensed observations of surface reflectance. We used a spatial correlation model describing water surface topography to illustrate the application of our framework. Nondimensional relations between model parameters and flow intensity were established based on a prior flume study. Expressing the model in the spatial frequency domain allowed us to use an efficient Fourier transform‐based algorithm for simulating water surfaces. Realizations for both flume and field settings had water surface slope distributions positively correlated with velocity and water surface roughness. However, most surface facets were gently sloped and thus unlikely to yield strong specular reflections; the model exaggerated the extent of water surface features, leading to underestimation of facet slopes. A ray tracing algorithm indicated that reflectance was greatest when solar and view zenith angles were equal and the sensor scanned toward the Sun to capture specular reflections of the solar beam. Reflected energy was concentrated in a small portion of the sky, but rougher water surfaces reflected rays into a broader range of directions. Our framework facilitates flight planning to avoid surface‐reflected radiance while mapping other river attributes, or to maximize this component to exploit relationships between hydraulics and surface reflectance. This initial analysis also highlighted the need for improved models of water surface topography in natural rivers.

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Section: Discussionmentioning

confidence: 99%

A framework for modeling connections between hydraulics, water surface roughness, and surface reflectance in open channel flows

2017

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“…The details of these measurements have been described in Ref. 19. The directivity pattern of the same ultrasonic transducer used for this work was found to be approximated by the far-field directivity of a vibrating piston with radius r a ¼ 20 mm inserted in a rigid infinite baffle, i.e., 20 …”

Section: A Acoustic Setupmentioning

confidence: 99%

Doppler spectra of airborne ultrasound forward scattered by the rough surface of open channel turbulent water flows

Dolcetti

Krynkin

2017

The Journal of the Acoustical Society of America

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Experimental data are presented on the Doppler spectra of airborne ultrasound forward scattered by the rough dynamic surface of an open channel turbulent flow. The data are numerically interpreted based on a Kirchhoff approximation for a stationary random water surface roughness. The results show a clear link between the Doppler spectra and the characteristic spatial and temporal scales of the water surface. The decay of the Doppler spectra is proportional to the velocity of the flow near the surface. At higher Doppler frequencies the measurements show a less steep decrease of the Doppler spectra with the frequency compared to the numerical simulations. A semi-empirical equation for the spectrum of the surface elevation in open channel turbulent flows over a rough bed is provided. The results of this study suggest that the dynamic surface of open channel turbulent flows can be characterized remotely based on the Doppler spectra of forward scattered airborne ultrasound. The method does not require any equipment to be submerged in the flow and works remotely with a very high signal to noise ratio.

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Robust reconstruction of scattering surfaces using a linear microphone array

Dolcetti

Alkmim

Cuenca

et al. 2021

Journal of Sound and Vibration

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Acoustic imaging in application to reconstruction of rough rigid surface with airborne ultrasound waves

Cited by 9 publications

References 21 publications

A framework for modeling connections between hydraulics, water surface roughness, and surface reflectance in open channel flows

A framework for modeling connections between hydraulics, water surface roughness, and surface reflectance in open channel flows

Doppler spectra of airborne ultrasound forward scattered by the rough surface of open channel turbulent water flows

Robust reconstruction of scattering surfaces using a linear microphone array

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