Proceedings of the Thirty-second (2022) International Ocean and Polar Engineering ConferenceShanghai, China, June 5–10, 2022
Copyright © 2022 by the International Society of Offshore and Polar Engineers (ISOPE)
ISBN 978-1-880653-81-4; ISSN 1098-6189

www.isope.org

Numerical Study of Wave-Structure Interaction with HOS-CFD MethodYuan Zhuang1, Jianhua Wang1*, Wenjun Zhou2, Cong Liu2, Decheng Wan1
1 State Key Laboratory of Ocean Engineering, School of Naval Architecture,
Ocean and Civil Engineering, Shanghai Jiao Tong University, Shanghai, China
2 Marine Design and Research Institute of China, Shanghai, China* Corresponding Author

computational domain, for example, Helmholtz velocity decomposing
theorem (Morino, 1986) is a common functional-decomposition
coupling method. Dommermuth (1998) applied this method intohydrodynamic problem, and he used this method to study the bow wave.
Zhao et al(2016, 2017) applied Helmholtz velocity decomposing
theorem into the open source software OpenFOAM, solving the flow
around the SUBOFF and a cylinder. Another functional-decomposition
coupling method is SWENSE (Spectral Wave Explicit Navier-Stokes
Equations) (Ferrant, 2002, 2003). This method divided thecomputational variables into incident variables and radiation variables.
The domain-decomposition coupling method combined potential
computational domain and viscous computational domain together, justmatch the boundary condition of these two methods. The advantage ofdomain-decomposition method is the ability to achieve the two-way
coupling easily. For example, Kim et al (2010) applied two-way couplingof BEM and VOF method to study the random waves. However, the twoway coupling method is still complex and cost time on the iterate solution.
Therefore, many studies applied one-way coupling method, such as
Lachaume et al (2003) and Biausser et al (2003, 2004). They combined
BEM and VOF to solve the wave propagating on the slope. In general,the potential-viscous method applied BEM method as the potential
method. However, Ducrozet et al (2014) mentioned that BEM methodneeds to be improved in efficiency.

ABSTRACTIn the present work, a HOS-CFD coupled method is validated with wavestructure interaction. The HOS-CFD method is applied to simulate afixed CALM buoy in regular waves with overset grids. Firstly, a periodic
wave simulation is carried out to make a better parameter choice in HOSCFD method combined with overset grids. Secondly, the forces andscattered waves around the CALM buoy are obtained throughcomputations. The results are compared with experimental results tovalidated the coupled method. The results of the numerical method arecompared with other numerical methods, including CFD methods andother potential-viscous methods. It is shown that the coupled methodwith overset technique is reliable in predicting wave-structureinteractions. At last, a Q-criterion and liutex view of turbulence flow areconsidered both in overset grids and static grids, give the difference
between these two mesh generations in HOS-CFD coupled method.

KEY WORDS: HOS; HOS-CFD coupled method; naoe-FOAM-SJTU
solver; CALM buoy

INTRODUCTION
With the developing and exploiting marine resources into deep sea, thestudy of hostile environment and wave-structure interaction became
essential. The floating platforms in deep sea may face freak waves which
induce large movement. Traditional CFD method with dynamic meshtechnique may have some weaknesses in solving this kind of problem,for example, source cost due to long-time simulation and mesh break due
to large motion amplitude. Therefore, a new coupled method on studying
wave and structure interaction is required. As we want to solve this kindof problem efficiently and accurately, the viscous effect around the bodyneed to be included. Thus, the potential-viscous coupled method isadopted, including the overset grid method.

In the present work, we combine our in-house CFD solver naoe-FOAMSJTU with a pseudo-spectral method High-Order-Spectral method(HOS). HOS method is a pseudo-spectral method (Dommermuth, D.G.
and Yue, D.K.P, 1987). It based on the partial difference equation ondynamic and kinematic free surface boundary condition. The potential
on the surface are wrote in a perturbation series and expanded each orderin a Taylor series. Thanks to the Fast Fourier Transform (FFT), thecommunication between discretization space and modal space is very
fast. With the given initial variables, the unknown potential can beobtained. Therefore, HOS method can generate nonlinear wave in a fastand efficient way. The combination of CFD method and HOS have donein previous work (Zhuang et al, 2018, 2021), including freak wave withship motion interaction (Zhuang et al, 2020) and combination withoverset grids (Zhuang et al, 2020). The HOS-CFD coupled method with

The coupling method of potential and viscous method can be divided into
two categories, functional-decomposition coupling and domaindecomposition coupling (Li, 2018). The functional-decomposition
coupling method considered solving the whole problem in the same2470