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 Gérard C. Nihous.The Method of Imbedded Lagrangian Element to Estimate Wave Power Absorption by Some Submerged Devices[J].Journal of Marine Science and Application,2014,(2):134-142.[doi:10.1007/s11804-014-1247-9]
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The Method of Imbedded Lagrangian Element to Estimate Wave Power Absorption by Some Submerged Devices


The Method of Imbedded Lagrangian Element to Estimate Wave Power Absorption by Some Submerged Devices
Gérard C. Nihous
Gérard C. Nihous
Department of Ocean and Resources Engineering, University of Hawaii, Honolulu HI 96822, USA
hydrodynamics wave power absorption wave energy conversion power take-off (PTO) Lagrangian element (LE) hydrodynamic coefficients
A simple approach is described to estimate the wave power absorption potential of submerged devices known to cause wave focusing and flow enhancement. In particular, the presence of a flow-through power take-off (PTO) system, such as low-head turbines, can be accounted for. The wave radiation characteristics of an appropriately selected Lagrangian element (LE) in the fluid domain are first determined. In the limit of a vanishing mass, the LE reduces to a patch of distributed normal dipoles. The hydrodynamic coefficients of this virtual object are then input in a standard equation of motion where the effect of the PTO can be represented, for example, as a dashpot damping term. The process is illustrated for a class of devices recently proposed by Carter and Ertekin (2011), although in a simplified form. Favorable wave power absorption is shown for large ratios of the LE wave radiation coefficient over the LE added mass coefficient. Under optimal conditions, the relative flow reduction from the PTO theoretically lies between 0.50 and ≈ 0.71, with lower values corresponding to better configurations. Wave power capture widths, the sensitivity of results to PTO damping and sample spectral calculations at a typical site in Hawaiian waters are proposed to further illustrate the versatility of the method.


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Unsponsored (cost share) contribution to the U.S. Department of Energy through the Hawaii National Marine Renewable Energy Center (Hawaii Natural Energy Institute, University of Hawaii), Account No. 6658090.
Last Update: 2014-06-10