A CFD-FEM analysis for Anaconda WEC with mooring lines


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




Wave energy converter, Fluid-structure interaction, Computational fluid dynamics, Finite element method, Anaconda


Anaconda wave energy converter (WEC) [1] is a typical flexible tube WEC design. In the past decade, the hydro-elastic performance of Anaconda model has been studied through experiments [2-3] and reduced-order numerical simulations [4-5]. However, to date, most of the undertaken research assumes that both ends of the tube are fixed, neglecting mooring lines that exist at designed conditions. The tube is allowed to move freely head to waves when mooring lines are considered. This is evident by an experiment conducted by Checkmate Flexible Engineering Ltd., where they observed a significant heave motion of Anaconda WEC, which may impact the dynamic response of WEC and further the energy conversion [6]. In our previous work [7], supported by the EPSRC project BASM-WEC (No. EP/V040553/1), a coupled numerical analysis tool using computational fluid dynamics (CFD) and finite element method (FEM) has been proposed to perform a numerical study for an Anaconda WEC model without considering mooring lines.
In this paper, the coupled fluid-structure interaction (FSI) analysis tool [7] based on CFD-FEM method will be used to investigate Anaconda WEC with mooring lines. To account for the effects of free motion of WEC, we develop a sub-module to be embedded into the existing tool. The fluid and structure are solved by a two-phase CFD solver developed based on OpenFOAM and a three-dimensional FEM code CalculiX, respectively. The strong coupling between OpenFOAM and CalculiX is achieved by a multi-physics coupling tool preCICE.
For the flexible tube, a commercial Natural Rubber material is studied. The hyper-elastic model YEOH is utilized to describe the nonlinear behaviour of material, and the model constants are calculated from the bi-axial tests. With the tool developed, numerical simulations are performed for different given regular waves. The flow details, velocity and pressure variation, structure deformation and stress distribution will be fully examined to better understand energy conversion performance of Anaconda WEC with mooring lines.

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[2] 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.
[3] Heller V, Chaplin J R, Farley F J M, et al. Physical model tests of the anaconda wave energy converter[C]//Proc. 1st IAHR European Congress. 2000.
[4] Farley F J M, Rainey R C T, Chaplin J R. Rubber tubes in the sea[J]. Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences, 2012, 370(1959): 381-402.
[5] Babarit A, Singh J, Mélis C, et al. A linear numerical model for analysing the hydroelastic response of a flexible electroactive wave energy converter[J]. Journal of Fluids and Structures, 2017, 74: 356-384.
[6] Checkmate Flexible Engineering, https://www.checkmateukseaenergy.com/, accessed 15th December 2022.
[7] Huang Y, Xiao Q, Idarraga G, et al. Numerical analysis of flexible tube wave energy converter using CFD-FEA method[C]//International Conference on Offshore Mechanics and Arctic Engineering. American Society of Mechanical Engineers, 2023 (submitted).



How to Cite

Y. Huang, “A CFD-FEM analysis for Anaconda WEC with mooring lines ”, Proc. EWTEC, vol. 15, Sep. 2023.