Characteristics of the velocity profile at tidal-stream energy sites

Authors

M. Lewis
S. P. Neill
P. Robins
Mohammad Reza Hashemi, University of Rhode IslandFollow
S. Ward

Document Type

Article

Date of Original Version

2018

Department

Ocean Engineering

Abstract

Realistic oceanographic conditions are essential to consider in the design of resilient tidal-stream energy devices that can make meaningful contributions to global emissions targets. Depth-averaged or simplified velocity profiles are often used in studies of device performance, or device interaction with the environment. We improve representation of flow at tidal-stream energy regions by characterising the velocity profile. At two potential tidal-stream energy sites, the 1/7th power-law with a bed-roughness coefficient of 0.4 accurately described the observed velocity profile on average (>1 month ADCP deployments). Temporal variability in the power-law fit was found at both sites, and best characterised with Generalised Extreme Value distribution; with correlation of variability to tidal condition, wind speed and wave conditions found. The mean velocity profile was accurately simulated using a 3D hydrodynamic model (ROMS) of the Irish Sea (UK) but with temporal variability in accuracy of power-law fits. For all potential tidal sites, the spatial-mean velocity profile was also found to be similar (characterised with ∼1/7th power-law and 0.4 bed-roughness value). Therefore realistic flow conditions can be characterised for tidal-energy research, but dynamically coupled wind-wave-tide models, or long-term observations, are needed to fully characterise velocity profile temporal variability.

Publication Title, e.g., Journal

Renewable Energy

Volume

114

Citation/Publisher Attribution

Lewis, M., Neill, S. P., Robins, P., Hashemi, M. R., & Ward, S. (2017). Characteristics of the velocity profile at tidal-stream energy sites. Renewable Energy, 114, 258-272. https://doi.org/10.1016/j.renene.2017.03.096

Available at: https://doi.org/10.1016/j.renene.2017.03.096

Creative Commons License

This work is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 4.0 License.