Spectral element FNPF simulation of focused wave groups impacting a fixed FPSO

Allan P. Engsig-Karup, Claes Eskilsson

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For the assessment of experimental measurements of focused wave groups impacting a surface-piecing fixed structure, we present a new Fully Nonlinear Potential Flow (FNPF) model for simulation of unsteady water waves. The FNPF model is discretized in three spatial dimensions (3D) using high-order prismatic - possibly curvilinear -elements using a spectral element method (SEM) that has support for adaptive unstructured meshes. This SEM-FNPF model is based on an Eulerian formulation and deviates from past works in that a direct discretization of the Laplace problem is used making it straightforward to handle accurately floating structural bodies of arbitrary shape. Our objectives are; i) present detail of a new SEM modelling developments and ii) to consider its application to address a wave-body interaction problem for nonlinear design waves and their interaction with a modelscale fixed Floating Production, Storage and Offloading vessel (FPSO). We first reproduce experimental measurements for focused design waves that represent a probably extreme wave event for a sea state represented by a wave spectrum and seek to reproduce these measurements in a numerical wave tank. The validated input signal based on measurements is then generated in a NWT setup that includes the FPSO and differences in the signal caused by nonlinear diffraction is reported.

Original languageEnglish
Title of host publicationProceedings of the 28th International Ocean and Polar Engineering Conference — 2018
PublisherInternational Society of Offshore & Polar Engineers
Publication date2018
ISBN (Print)978-1-880653-87-6
Publication statusPublished - 2018
Event28th International Ocean and Polar Engineering Conference (ISOPE 2018) - Sapporo, Japan
Duration: 10 Jun 201815 Jun 2018


Conference28th International Ocean and Polar Engineering Conference (ISOPE 2018)
SeriesProceedings of the International Offshore and Polar Engineering Conference


  • Spectral element method
  • High order numerical methods
  • Unstructured meshes
  • Fully nonlinear potential flow
  • Focused wave groups
  • Wave-body interaction
  • FPSO

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