Abstract
This paper analyses the nonlinear forces on a moored point-absorbing wave energy converter (WEC) in resonance at prototype scale (1:1) and at model scale (1:16). Three simulation types were used: Reynolds Averaged Navier-Stokes (RANS), Euler and the linear radiation-diffraction method (linear). Results show that when the wave steepness is doubled, the response reduction is: (i) 3% due to the nonlinear mooring response and the Froude-Krylov force; (ii) 1-4% due to viscous forces; and (iii) 18-19% due to induced drag and non-linear added mass and radiation forces. The effect of the induced drag is shown to be largely scale-independent. It is caused by local pressure variations due to vortex generation below the body, which reduce the total pressure force on the hull. Euler simulations are shown to be scale-independent and the scale effects of the WEC are limited by the purely viscous contribution (1-4%) for the two waves studied. We recommend that experimental model scale test campaigns of WECs should be accompanied by RANS simulations, and the analysis complemented by scale-independent Euler simulations to quantify the scale-dependent part of the nonlinear effects.
Originalsprog | Engelsk |
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Artikelnummer | 124 |
Tidsskrift | Journal of Marine Science and Engineering |
Vol/bind | 6 |
Udgave nummer | 4 |
Antal sider | 22 |
ISSN | 2077-1312 |
DOI | |
Status | Udgivet - 22 okt. 2018 |
Bibliografisk note
Special Issue Nonlinear Numerical Modelling of Wave Energy Converters.Emneord
- Wave energy
- Point absorber
- Scale effects
- Viscous drag
- Induced drag
- Computational fluid dynamics