Near bed turbulence measurement with acoustic doppler velocimeter (ADV)

Sulaiman, Mohd Sofiyan; Sinnakaudan, Shanker Kumar; Shukor, Mohd Rizal

doi:10.1007/s12205-013-0084-8

Cited by 15 publications

(6 citation statements)

References 35 publications

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“…Mechanisms for turbulence generation within laboratory settings include varying the degree of flume boundary roughness, 32 modulation of flow pumps, 33 and the positioning of cylindrical or spherical flow obstructions ('bluff bodies') within the flow field. 34,35 Turbulent properties may be then quantified through point measurements of velocity sampled at high frequencies (e.g., 20 Hz) using a range of sensor types 26,[36][37][38][39][40] or visualized and estimated using particle image velocimetry (PIV) which is more straightforward to implement in the laboratory than in the field. [41][42][43][44] Recent advances in acoustic Doppler current profiling can provide detailed three-dimensional hydraulics by capturing high-resolution vertical profiles of semicontinuous velocity points.…”

Section: Approaches To Research Designmentioning

confidence: 99%

Life in turbulent flows: interactions between hydrodynamics and aquatic organisms in rivers

et al. 2017

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The turbulent properties of flow in rivers are of fundamental importance to aquatic organisms yet are rarely quantified during routine river habitat assessment surveys or the design of restoration schemes due to their complex nature. In this paper, we review the two-way interactions between aquatic biota and hydrodynamics in rivers, and key methodological approaches used in their quantification, to encourage more explicit consideration of the importance of turbulence in river science and management. We explore recent advances and issues relating to the study of these interactions in the field, laboratory and numerical modeling, the use of artificial and live biota, and different flow measurement technologies. We also review methods for the quantification of ecologically relevant turbulent flow properties, identifying key descriptors of the intensity, periodicity, orientation, and the scale of turbulent flow structures. Our analysis highlights not only the various ways in which plants and animals modify the flow field but also how this can deliver beneficial effects relating to solute exchange, food availability, oxygenation, waste removal, locomotion, and predator-prey interactions. It also demonstrates potential threats to growth and survival relating to turbulence, including injury, dislodgement, increased energy expenditure, mortality, and complex influences on predators and prey. We conclude by identifying some remaining barriers to the integration of turbulence into the science and practice of river assessment and restoration but also opportunities in the form of controlled laboratory experimentation, increasingly sophisticated flow sensors and imaging technologies, and numerical simulation of turbulence that could advance understanding in this complex field of research.There is considerable diversity in the research approaches applied to the study of interactions FIGURE 1 | Definition of Reynolds number and laminar and turbulent flow, with example Reynolds numbers for different types of organisms interacting with the flow. Advanced Reviewwires.wiley.com/water

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Section: Approaches To Research Designmentioning

confidence: 99%

Life in turbulent flows: interactions between hydrodynamics and aquatic organisms in rivers

et al. 2017

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“…The ADV data were first curated by removing measurements not complying with threshold values of 15 dB for beam signalto-noise ratio (SNR) and 70% for correlation (Sulaiman et al, 2013). The acceleration threshold method (Goring and Nikora, 2002) was then used to de-spike the data.…”

Section: Discussionmentioning

confidence: 99%

Anchor Forces on Coir-Based Artificial Seagrass Mats: Dependence on Wave Dynamics and Their Potential Use in Seagrass Restoration

2022

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Seagrasses represent an essential part of the coastal environment and are hence the target of many coastal restoration projects. Artificial seagrass (ASG) mats may facilitate seagrass growth, making them a captivating option for restoration projects. However, little is known about the forces occurring on mats deployed in marine environments and especially on how these forces are transmitted to the anchoring points. Here, we present a study of prototype biodegradable coconut-mesh mats as base layer for ASG meadows and investigate the forces that occur at the anchors. We test the performance of three mesh types under wave forcing using two different anchor configurations without ASG and subsequently test ASG mats of one mesh type under wave forcing and a 4-anchor configuration to assess the effect of the ASG on anchor loading as a function of incident orbital velocities. We found that the mat composition plays a more important role than the number of anchors in anchor load reduction. The anchor forces were 2–4 times higher at front anchors compared to rear anchors, relative to wave propagation direction, and were also considerably higher in that direction compared to the opposite direction. With ASG, the forces increased compared to the highest measured forces without ASG. The forces on the anchors were almost fully dominated by the drag on the ASG based on material properties, ASG reconfiguration and flow conditions. We derive a relation between horizontal orbital velocities and expected forcing on the anchor based on ASG properties and the corresponding area of each anchor and discuss relevant criteria for the design of ASG mats. This should help to assess the loading on anchors deployed for restoration under specific site conditions and chosen materials.

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“…To validate the CPMTM and demonstrate its functionality, a direct comparison was carried out with an acoustic Doppler velocimeter (ADV) in a flume at the Ocean University of China. The ADV can measure three-dimensional instantaneous velocity, turbulence characteristics, and power spectral density and has been widely used in experimental flumes and fields [18][19][20]. A schematic of the experiment is presented in Figure 3.…”

Section: Laboratory Experimentsmentioning

confidence: 99%

A New Cross-Platform Instrument for Microstructure Turbulence Measurements

Nie

Yang

Song

et al. 2021

JMSE

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This study developed a new cross-platform instrument for microstructure turbulence measurement (CPMTM) and evaluated its performance. The CPMTM is designed as an “all-in-one” payload that can be easily integrated with a variety of marine instrumentation platforms. The sensors in the CPMTM include two shear probes, a fast-response temperature probe, and an accelerometer for monitoring vibrations. In addition, a custom-designed flexible connection vibration-damping device is used to isolate platform vibrations. To validate the CPMTM performance, a direct comparison was carried out with a reference acoustic Doppler velocimeter in a controlled flume for four background turbulence levels. The results of the comparison show that the velocity spectra measured by the CPMTM and ADV w components are in agreement, which demonstrates the ability of the CPMTM to acquire accurate turbulence data. Furthermore, the CPMTM was integrated into the long-range Sea-Whale 2000 AUV and tested in the northern South China Sea in September 2020. The data collected by the CPMTM show that the measured shear spectrum of the noise reduction agrees well with the empirical Nasmyth spectrum. Turbulent kinetic energy dissipation rates as low as 7 × 10−10 W kg−1 can be resolved. Laboratory and field experiments illustrate that the CPMTM has an extraordinarily low noise level and is validated for turbulence measurements.

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Near bed turbulence measurement with acoustic doppler velocimeter (ADV)

Cited by 15 publications

References 35 publications

Life in turbulent flows: interactions between hydrodynamics and aquatic organisms in rivers

Life in turbulent flows: interactions between hydrodynamics and aquatic organisms in rivers

Anchor Forces on Coir-Based Artificial Seagrass Mats: Dependence on Wave Dynamics and Their Potential Use in Seagrass Restoration

A New Cross-Platform Instrument for Microstructure Turbulence Measurements

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