<p>Computational Fluid Dynamics (CFD) tools are widely used to simulate wave and structure interactions in marine &amp; offshore industry. However, conventional CFD tools require significant computational resources. This is largely due to the requirement of large computational domain to ensure adequate development of nonlinear wave evolutions as well as to avoid boundary effects resulting from wave interacting with any fixed or floating structures in the domain. Furthermore, very fine mesh elements are required to avoid excessive numerical dissipation during wave propagation. All of these factors will significantly increase the computational costs, resulting in the conventional CFD approaches being impractical for simulations of wave-structure interactions over a long duration.<br>
In this study, a coupled potential flow and CFD model is developed to reduce the simulation cost. The model decomposes the simulation domain into far-field and near-field region. Wave propagation in the far-field region is simulated by a potential flow solver (implemented using the High-Order Spectral or HOS method), while the wave-structure interactions in the near-field region are simulated by a fully nonlinear, viscous, and two-phase CFD solver (Star-CCM+). A forcing zone is distributed between the two regions to blend the computational outputs from the potential flow into the CFD solvers. The coupling algorithm has been developed to improve the accuracy and efficiency. For example, instead of interpolating surface elevation and velocity fields from the HOS in space within the CFD forcing zone, these fields are computed directly using the Fourier components from the HOS to improve the accuracy. The computed values are stored in memory in each time step to improve the efficiency. Further details of these developments within the coupling algorithm will be elaborated in the paper.<br>
The coupled solver is applied to simulate three cases, namely regular wave propagation, irregular wave propagation, and regular wave interaction with a vertical cylinder. The accuracy and efficiency of the coupled solver will be demonstrated through these cases, which also serve as verification and validation of the results. Finally, a simulation of a 3D wave encountering an FPSO (Floating Production&nbsp;Storage and Offloading) unit will also be presented.</p>

Coupling of Potential Flow and Cfd Model for Fluid and Structure Interactions

Paper Proceedings: https://asmedigitalcollection.asme.org/OMAE/OMAE2021/volume/85116

OMAE 2021

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