Rates of Dissipation of Turbulent Kinetic Energy in a High Reynolds Number Tidal Channel

McMillan, J.; Hay, Alex E.; Lueck, Rolf G.; Wolk, Fabian

doi:10.1175/jtech-d-15-0167.1

Cited by 42 publications

(47 citation statements)

References 23 publications

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“…However, turbulence is highly intermittent in both space and time, and field studies show that it varies greatly throughout the mixed layer and the pycnocline ( 25 ). Our values are also comparable to those measured in many plankton habitats, e.g., coastal zones and estuaries where

reaches

m 2

( 26 , 27 ).…”

Section: Resultssupporting

confidence: 87%

Zooplankton can actively adjust their motility to turbulent flow

Michalec¹,

Fouxon²,

Souissi

et al. 2017

Proc. Natl. Acad. Sci. U.S.A.

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SignificanceZooplankton possess narrow swimming capabilities, yet are capable of active locomotion amid turbulence. By decoupling the relative velocity of swimming zooplankton from that of the underlying flow, we provide evidence for an active adaptation that allows these small organisms to modulate their swimming effort in response to background flow. This behavioral response results in reduced diffusion at substantial turbulence intensity. Adjusting motility provides fitness advantage because it enables zooplankton to retain the benefits of self-locomotion despite the constraints enforced by turbulence transport. Vigorous swimming and reduced diffusion oppose turbulence advection, can directly affect the dispersal of zooplankton populations, and may help these organisms to actively control their distribution in dynamic environments.

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reaches

m 2

( 26 , 27 ).…”

Section: Resultssupporting

confidence: 87%

Zooplankton can actively adjust their motility to turbulent flow

Michalec¹,

Fouxon²,

Souissi

et al. 2017

Proc. Natl. Acad. Sci. U.S.A.

View full text Add to dashboard Cite

show abstract

“…Further evidence that the upper MAVS sits within the surface layer when the mean flow speed is greater than 10 cm/s comes from the scaling of the TKE dissipation rate with mean flow speed. At these flow speeds, the TKE dissipation rate is broadly proportional to |u| 3 (grey line in Figure 7a), which is the expected scaling for a turbulent flow in the surface layer where turbulent production and dissipation are broadly balanced (J. M. McMillan et al, 2016).…”

Section: 1029/2019jc015164mentioning

confidence: 57%

Turbulence Observations Beneath Larsen C Ice Shelf, Antarctica

Davis

Nicholls

2019

JGR Oceans

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Increased ocean‐driven basal melting beneath Antarctic ice shelves causes grounded ice to flow into the ocean at an accelerated rate, with consequences for global sea level. The turbulent transfer of heat through the ice shelf‐ocean boundary layer is critical in setting the basal melt rate, yet the processes controlling this transfer are poorly understood and inadequately represented in global climate models. This creates large uncertainties in predictions of future sea level rise. Using a hot‐water drilled access hole, two turbulence instrument clusters (TICs) were deployed 2.5 and 13.5 m beneath Larsen C ice shelf in December 2011. Both instruments returned a yearlong record of turbulent velocity fluctuations, providing a unique opportunity to explore the turbulent processes within the ice shelf‐ocean boundary layer. Although the scaling between the turbulent kinetic energy (TKE) dissipation rate and mean flow speed varies with distance from the ice shelf base, at both TICs the TKE dissipation rate is balanced entirely by the rate of shear production. The freshwater released by basal melting plays no role in the TKE balance. When the upper TIC is within the log‐layer, we derive an under‐ice drag coefficient of 0.0022 and a roughness length of 0.44 mm, indicating that the ice base is smooth. Finally, we demonstrate that although the canonical three‐equation melt rate parameterization can accurately predict the melt rate for this example of smooth ice underlain by a cold, tidally forced boundary layer, the law of the wall assumption employed by the parameterization does not hold at low flow speeds.

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“…The number of published studies quantifying turbulence levels using in-situ field measurements at tidal energy test sites has increased in recent years [14][15][16][17][18][19][20]. Similar studies have been conducted in rivers [21][22][23], however, due to differences on the onset flow conditions, topography and sedimentation, the results of these studies is of limited relevance.…”

Section: Introductionmentioning

confidence: 99%

On the Variation of Turbulence in a High-Velocity Tidal Channel

2019

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This study presents the variation in turbulence parameters derived from site measurements at a tidal energy test site. Measurements were made towards the southern end of the European Marine Energy Centre’s tidal energy test site at the Fall of Warness (Orkney, Scotland). Four bottom mounted divergent-beam Acoustic Doppler Current Profilers (ADCPs) were deployed at three locations over an area of 2 km by 1.4 km to assess the spatial and temporal variation in turbulence in the southern entrance to the channel. During the measurement campaign, average flood velocities of 2 ms−1 were recorded with maximum flow speeds of 3 ms−1 in the absence of significant wave activity. The velocity fluctuations and turbulence parameters show the presence of large turbulent structures at each location. The easternmost profiler located in the wake of a nearby headland during ebb tide, recorded flow shielding effects that reduced velocities to almost zero and produced large turbulence intensities. The depth-dependent analysis of turbulence parameters reveals large velocity variations with complex profiles that do not follow the standard smooth shear profile. Furthermore, turbulence parameters based on data collected from ADCPs deployed in a multi-carrier frame at the same location and time period, show significant differences. This shows a large sensitivity to the make and model of ADCPs with regards to turbulence. Turbulence integral length scales were calculated, and show eddies exceeding 30 m in size. Direct comparison of the length scales derived from the streamwise velocity component and along-beam velocities show very similar magnitudes and distributions with tidal phase.

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Rates of Dissipation of Turbulent Kinetic Energy in a High Reynolds Number Tidal Channel

Cited by 42 publications

References 23 publications

Zooplankton can actively adjust their motility to turbulent flow

Zooplankton can actively adjust their motility to turbulent flow

Turbulence Observations Beneath Larsen C Ice Shelf, Antarctica

On the Variation of Turbulence in a High-Velocity Tidal Channel

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