Parametric excitation of moored wave energy converters using viscous and non-viscous CFD simulations
Paper in proceedings, 2018

The paper discusses the use of CFD simulations to analyse the parametric excitation of moored, full scale wave energy converters in six degrees of freedom. We present results of VOF- RANS and VOF-Euler simulations in Open FOAM® for two body shapes: (i) a truncated cylinder; and (ii) a cylinder with a smooth hemispherical bottom. Flow characteristics show large differences in smoothness of flow between the hull shapes, where the smoother shape results in a larger heave response. However the increased amplitude makes it unstable and parametric pitch excitation occurs with amplitudes up to 30°. The responses in surge, heave and pitch (including the transition to parametric motion) are found to be insensitive to the viscous effects. This is notable as the converters are working in resonance. The effect of viscous damping was visible in the roll motion, where the RANS simulations showed a smaller roll. However, the roll motion was found to be triggered not by wave-body interaction with the incident wave, but by reflections from the side walls. This highlights the importance of controlling the reflections in numerical wave tanks for simulations with WEC motion in six degrees of freedom.

Viscous effects

Parametric excitation

Mooring

CFD

Author

Johannes Palm

Chalmers, Mechanics and Maritime Sciences, Marine Technology

Claes Eskilsson

Aalborg University

Lars Bergdahl

Chalmers, Architecture and Civil Engineering, Water Environment Technology

Advances in Renewable Energies Offshore – Guedes Soares (Ed.) Taylor & Francis Group, London

455-462


Lissabon, Portugal,

Including Nonlinear and Viscous Effects when Modelling the Performance of Wave Energy Converters

Swedish Energy Agency, 2015-08-01 -- 2017-02-28.

Driving Forces

Sustainable development

Areas of Advance

Energy

Infrastructure

C3SE (Chalmers Centre for Computational Science and Engineering)

Subject Categories

Fluid Mechanics and Acoustics

Marine Engineering

More information

Created

11/5/2018