NHESS Natural Hazards and Earth System Sciences NHESS Nat. Hazards Earth Syst. Sci. 1684-9981 Copernicus Publications Göttingen, Germany 10.5194/nhess-11-519-2011 Numerical simulation of floating bodies in extreme free surface waves Hu Z. Z. 1 Causon D. M. 1 Mingham C. G. 1 Qian L. 1 Centre for Mathematical Modelling and Flow analysis, School of Computing, Mathematics and Digital Technology, The Manchester Metropolitan University, Manchester, M1 5GD, UK 16 02 2011 11 2 519 527 Copyright: © 2011 Z. Z. Hu et al. 2011 This work is licensed under the Creative Commons Attribution 3.0 Unported License. To view a copy of this licence, visit https://creativecommons.org/licenses/by/3.0/ This article is available from https://nhess.copernicus.org/articles/11/519/2011/nhess-11-519-2011.html The full text article is available as a PDF file from https://nhess.copernicus.org/articles/11/519/2011/nhess-11-519-2011.pdf

In this paper, we use the in-house Computational Fluid Dynamics (CFD) flow code AMAZON-SC as a numerical wave tank (NWT) to study wave loading on a wave energy converter (WEC) device in heave motion. This is a surface-capturing method for two fluid flows that treats the free surface as contact surface in the density field that is captured automatically without special provision. A time-accurate artificial compressibility method and high resolution Godunov-type scheme are employed in both fluid regions (air/water). The Cartesian cut cell method can provide a boundary-fitted mesh for a complex geometry with no requirement to re-mesh globally or even locally for moving geometry, requiring only changes to cut cell data at the body contour. Extreme wave boundary conditions are prescribed in an empty NWT and compared with physical experiments prior to calculations of extreme waves acting on a floating Bobber-type device. The validation work also includes the wave force on a fixed cylinder compared with theoretical and experimental data under regular waves. Results include free surface elevations, vertical displacement of the float, induced vertical velocity and heave force for a typical Bobber geometry with a hemispherical base under extreme wave conditions.

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