Session: 09-02-03: Wave Energy - Design and Performance Analysis 2

Paper Number: 101302

101302 - Numerical Analysis of Flexible Tube Wave Energy Convertor Using Cfd-Fea Method 

With the development of wave energy converters (WECs), the application of flexible structures in the WECs has recently attracted attention. Different flexible WECs’ designs have been proposed to improve the performance in terms of fatigue life, survivability and adaptability of the devices to the dynamic condition of the sea. One of the most widely studied designs is the flexible tube WEC, which is able to absorb wave energy within a wider range of wave frequencies.  A low-order reduced approach based on potential flow theory and one-dimensional elastic tube method has been proposed to study the performance of flexible tube WEC with varying parameters [1]. However, non-linear phenomena induced by wave-structure interactions and hyper-elastic material are ignored. In addition, flow details around the WEC and stress distribution in the flexible structure cannot be obtained from the simplified method, preventing a deeper understanding of the performance of the flexible tube WEC in ocean waves. It is therefore necessary to study the detailed responses of the flexible tube WEC with different materials to improve the performance.

In this study, a coupled numerical analysis tool is developed to study the mechanical response of flexible WEC for given wave conditions. The flexible deformation of the structure is analysed by an open-source three-dimensional (3D) finite element code CalculiX [2]. The fluid flow around the WEC is solved by a two-phase CFD solver [3] developed based on OpenFOAM [4]. The two-way coupling between OpenFOAM and CalculiX is achieved by using a multi-physics code coupling tool preCICE [5]. On the other hand, the hyperelastic parameters of the flexible materials required by the analysis is obtained based on the mechanical characterisation of the elastomers under different loading conditions.

In the present work, a typical flexible tube WEC concept, Anaconda [6], is selected as the analysis object. Numerical simulations are performed for Anaconda WEC with two different commercial flexible materials, Latex and Styrene-Butadiene Rubber (SBR), for the given regular wave conditions. Fluid-flexible-structure interaction responses of the Anaconda WEC are compared considering the impact of the flexible materials on the performance of the device. The flow details around the WEC, velocity and pressure variation in the flexible tube, structure deformation, and stress distribution are fully explored.

 

References

[1]    Chaplin J R, Heller V, Farley F J M, et al. Laboratory testing the Anaconda[J]. Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences, 2012, 370(1959): 403-424.

[2]    Dhondt G. Calculix crunchix user’s manual version 2.12[J]. Munich, Germany, accessed Sept, 2017, 21: 2017.

[3]    Higuera P. olaFlow: CFD for waves[J]. URL https://doi. org/10.5281/zenodo, 2017, 1297013.

[4]    Jasak H, Jemcov A, Tukovic Z. OpenFOAM: A C++ library for complex physics simulations[C]//International workshop on coupled methods in numerical dynamics. IUC Dubrovnik Croatia, 2007, 1000: 1-20.

[5]    Bungartz H J, Lindner F, Gatzhammer B, et al. preCICE–a fully parallel library for multi-physics surface coupling[J]. Computers & Fluids, 2016, 141: 250-258.

[6]    Chaplin J R, Farley F J M, Rainey R C T. Power Conversion in the ANACONDA WEC[C]//Proc 22nd Intl. Workshop on Water Waves and Floating Bodies. 2007.

Presenting Author: Guillermo Idarraga University of Strathclyde

Presenting Author Biography: NA

Authors:

Yang Huang University of Strathclyde
Qing Xiao University of Strathclyde
Guillermo Idarraga University of Strathclyde
Liu Yang University of Strathclyde
Saishuai Dai University of Strathclyde
Farhad Abad University of Strathclyde
Feargal Brennan University of Strathclyde
Saeid Lotfian University of Strathclyde