Comparative evaluation of PML technique for hydrodynamic impact loading on spar-type floating platform

• Published in: Ocean engineering Vol. 85; pp. 80 - 92
• Main Authors: Kim, M.S., Jeon, S.H., Cho, J.R., Jeong, W.B.
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 15.07.2014; Elsevier
• Subjects: Applied sciences; Buildings. Public works; Computational fluid dynamics; Exact sciences and technology; Floating platform; Floating platforms; Fluid flow; Hydraulic constructions; Hydrodynamic impact; Hydrodynamics; Joining; Mathematical analysis; Mathematical models; Non-reflective boundary treatment; Offshore structure (platforms, tanks, etc.); Offshore wind turbine; Perfectly matched layer (PML); Rigid-body dynamics; Structural stability; Non-reflective boundary treatment; Offshore wind turbine; Hydrodynamic impact; Structural stability; Floating platform; Perfectly matched layer (PML); Dynamic response; Hydrodynamic force; Wind generator; Fluid structure interaction; Modeling; Perfectly matched layer; Numerical simulation; Offshore structure; Spar platform
• ISSN: 0029-8018; 1873-5258
• DOI: 10.1016/j.oceaneng.2014.04.026

The structural dynamic stability of spar-type floating platform for offshore wind turbine subject to hydrodynamic impact is numerically investigated by the dynamic response analysis. The unbounded flow domain of sea water is truncated to a bounded finite domain and the reflection of out-going hydrodynamic impact wave at the artificial boundary of truncated domain is minimized by the perfectly matched layer (PML) technique. The generalized transport equations governing the non-viscous compressible water flow is split into three PML equations by introducing the direction-wise absorption coefficients and the state variables. The coupled fluid–structure interaction problem is approximated by the iterative Eulerian FVM–Lagrangian FEM with the Euler–Lagrange coupling scheme. The impact-induced hydrodynamic pressure is calculated by the JWL equation of state and the mixture of un-reacted explosive and reaction products is defined by the reacted volume fraction. It is confirmed from the numerical experiments that the wave reflection phenomenon at the artificial boundary is substantially reduced when compared with the case without using the PML technique. And, the remarkable amplitude difference and the fluctuation with several subsequent peaks in the time responses of rigid body motion and effective stress of the floating platform are successfully suppressed when PML layers are used. •The PML technique is comparatively evaluated for the hydrodynamic loading on spar-type floating platform.•Impact-induced hydrodynamic pressure between with and without the PML technique is compared.•The reflection of out-going waves at truncated boundary is substantially absorbed.•Time histories of six rigid body motions of floating platform are also compared.