Constraints on extractable power from energetic tidal straits

Evans, Paul; Mason-Jones, Allan; Wilson, Catherine; Wooldridge, Chris; O'Doherty, Timothy; O'Doherty, Daphne Maria

doi:10.1016/j.renene.2015.03.085

Cited by 51 publications

(42 citation statements)

References 29 publications

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“…A separated flow off this feature might go some way to explaining why we tend to see a maximum in TKE density roughly 5 m off the seabed in campaign B ebbs. A study of the mean flow in Ramsey Sound (Evans et al 2015) did not show variation in the gross flow characteristics on comparable spatial scales except in the wake of large surface-piercing features, however; so if the bathymetry is the cause then we must consider that certain features strongly influence the turbulence characteristics without a similarly strong effect on the mean flow.…”

Section: Discussionmentioning

confidence: 93%

“…The most important mean flow characteristics of this site, obtained from boat transects, have been previously reported in Fairley et al (2013) and Evans et al (2015). The bathymetry of the site is complex, with the centre of the channel running as deep as 70 m in places, a stack that pierces the surface at low water (Horse Rock) and a large ridge (the Bitches) extending from Ramsey Island into the middle of the channel (see Fig.…”

Section: Introductionmentioning

confidence: 81%

“…The mean flow velocity is greater on floods than on ebbs, by 4.2 % in campaign A and 34.4 % in campaign B (cf. Evans et al 2015).…”

Section: Methodsmentioning

confidence: 99%

“…2 depicts the bathymetry in the immediate vicinity of the measurement locations. Evans et al (2015) presents the bathymetry of Ramsey Sound in more detail.…”

Section: Introductionmentioning

confidence: 99%

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Micrositing variability and mean flow scaling for marine turbulence in Ramsey Sound

Togneri

Masters

2015

J. Ocean Eng. Mar. Energy

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We present turbulence results from two acoustic Doppler current profiler measurement campaigns carried out in Ramsey Sound at two locations within 50 m of one another. The first measurements were taken in 2009 and the second in 2011; both include a complete spring-neap cycle. In this paper we characterise turbulence through turbulent kinetic energy (TKE) density and integral lengthscales and their relationships with one another and with mean flow parameters. We briefly describe the methods used to calculate these parameters. We find that a flood-ebb asymmetry is present in the data from both measurement campaigns, but although the flood tides are similar at both locations, the ebb tides are much more energetic in the 2011 data than the 2009 data. We suggest that this may be due to differences in seabed features between the two measurement locations. Dimensional analysis is employed to investigate how TKE scales with mean flow velocity; we find that the expected quadratic scaling is not well supported by the data at either measurement location. As a consequence, flows that have more energetic turbulence may instead appear to be less turbulent if judged by turbulence intensity. We investigate the correlation between lengthscales and TKE density and find that it is highly site-specific: it should not be assumed that for a given measurement location highly energetic turbulence is associated with larger flow structures or vice versa.

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Section: Discussionmentioning

confidence: 93%

Section: Introductionmentioning

confidence: 81%

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Micrositing variability and mean flow scaling for marine turbulence in Ramsey Sound

Togneri

Masters

2015

J. Ocean Eng. Mar. Energy

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“…A recent ADCP study which measured the properties of complicated flow in Ramsey Sound (West Wales) confirms that flow fields are spatially heterogeneous in three dimensions. Thus using depth-averaged velocity data to compute TST power extraction could provide inaccurate estimations [15], highlighting the necessity of detailed flow modelling for TST deployment sites.…”

Section: Introductionmentioning

confidence: 99%

Computational Fluid Dynamics and Visualisation of Coastal Flows in Tidal Channels Supporting Ocean Energy Development

et al. 2015

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Flow characteristics in coastal regions are strongly influenced by the topography of the seabed and understanding the fluid dynamics is necessary before installation of tidal stream turbines (TST). In this paper, the bathymetry of a potential TST deployment site is used in the development of the a CFD (Computational Fluid Dynamics) model. The steady state k-and transient Large Eddy Simulation (LES) turbulence methods are employed and compared. The simulations are conducted with a fixed representation of the ocean surface, i.e., a rigid lid representation. In the vicinity of Horse Rock a study of the pressure difference shows that the small change in height of the water column is negligible, providing confidence in the simulation results. The stream surface method employed to visualise the results has important inherent characteristics that can enhance the visual perception of complex flow structures. The results of all cases are compared with the flow data transect gathered by an Acoustic Doppler Current Profiler (ADCP). It has been understood that the k-method can predict the flow pattern relatively well near the main features of the domain and the LES model has the ability to simulate some important flow patterns caused by the bathymetry.

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Marine Renewable Energy

Yang¹,

Copping²

2017

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Constraints on extractable power from energetic tidal straits

Cited by 51 publications

References 29 publications

Micrositing variability and mean flow scaling for marine turbulence in Ramsey Sound

Micrositing variability and mean flow scaling for marine turbulence in Ramsey Sound

Computational Fluid Dynamics and Visualisation of Coastal Flows in Tidal Channels Supporting Ocean Energy Development

Marine Renewable Energy

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