PSI - Issue 48

Nurman Firdaus et al. / Procedia Structural Integrity 48 (2023) 58–64 Firdaus et al. / Structural Integrity Procedia 00 (2023) 000–000

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 ݋  ݐ +  ሬԦ =    .   ሬԦ .   ݐ 2 .   ݋  ݐ +  ሬԦ =−   2 .   .   ሬԦ .   ݐ    ݐ +  ሬԦ =   .   .   ሬԦ .   ݐ

=   � =− .   � =

(12)

(13)

(14) where  is the body response in unit vector,  is the amplitude, and  ሬԦ is the phase shift. From above motion equation, the transfer function of the floating body can be simplified and summarized as follows, − 2 + ++  ො  = ෡  (15)     = ܣ =  ෡  − 2 + ++ (16)

Fig. 1. (a) Main dimension of OC3-Hywind; and (b) Mesh NEMOH for half spar of OC3-Hywind.

4. Validation results One of the important stages in the study is the validation process in modeling to ensure the calculation results are in accordance with the applicable theory (Firdaus, B. Djatmiko, et al., 2021). To review the feasibility of the present BEM-Solver NEMOH output and the assumption of the linearity within the domain, the validation method has been applied in the current work. We adopted the hydrodynamics model results of OC3-Hywind Spar FOWT with the BEM Model published by (Ma et al., 2021). The validation case in this section considered added mass and damping radiation coefficients. The size of platform model for validation setup is shown in Fig. 1(a). The properties parameters are listed as follows: FOWT’s mass  = 8.066E6 kg, Center of Gravity ݋ = -89.9 m, draft  = 120m, base diameter of platform spar  = 9.4 m and taper diameter of platform spar  =6.5m. The mesh considered for the hydrodynamic model to represent the body surface in the present paper have a total of 1900 panels. The platform model of Spar FOWT is discretised as in Fig.1(b). The numerical result based on the frequency-domain are compared with the previous reference,as shown in Fig.2. It is observed for all trend of curve that the present results has a good agreement with the reference data. The BEM-solver settings obtained the results of well correctness, this configuration in the BEM model calculation is used to compare the performances of various floater geometries for the next Spar FOWT.