Assessment of Scale Effects, Viscous Forces and Induced Drag on a Point-AbsorbingWave Energy Converter by CFD Simulations
Artikel i vetenskaplig tidskrift, 2018

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.

point absorber

computational fluid dynamics

scale effects

wave energy

induced drag

viscous drag

Författare

Johannes Palm

Chalmers, Mekanik och maritima vetenskaper, Marin teknik

Claes Eskilsson

Aalborg Universitet

Lars Bergdahl

Chalmers, Arkitektur och samhällsbyggnadsteknik, Vatten Miljö Teknik

Rickard Bensow

Chalmers, Mekanik och maritima vetenskaper, Marin teknik

Journal of Marine Science and Technology

1023-2796 (ISSN)

Vol. 2018 6 124-146

Ickelinjära och viskösa effekters inverkan på energiomvandlingen hos flytande vågkraftverk

Energimyndigheten, 2015-08-01 -- 2017-02-28.

Drivkrafter

Hållbar utveckling

Ämneskategorier

Teknisk mekanik

Farkostteknik

Strömningsmekanik och akustik

Styrkeområden

Energi

Fundament

Grundläggande vetenskaper

DOI

10.3390/jmse6040124

Mer information

Senast uppdaterat

2018-11-05