Comparative study of mathematical models for mooring systems coupled with CFD

Jiang, Changqing; Moctar, Ould el; Schellin, Thomas E.; Paredes, Guilherme Moura

doi:10.1080/17445302.2020.1790294

Cited by 11 publications

(6 citation statements)

References 14 publications

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“…Although accurate results were obtained using a morphing grid scheme in our previous works [19,20], for motions in rough sea conditions large mesh deformations were reported in our subsequent study [21], which yielded skewed shapes and unacceptable aspect ratios for grid cells and, consequently, induced numerical instabilities. To dispose of these limitations and still use the same mesh for our subsequent systematic simulations, we adopted the overset mesh scheme.…”

Section: The Viscous Flow Solvermentioning

confidence: 75%

“…Mooring line shape and tension were derived from the catenary formulation, based on the assumption that each mooring line is in static equilibrium at each time step and that inertia effects can be neglected. For further details of the adopted quasi-static (QS) model, see [21]. Figure 16 plots tensions in cables 1 and 2 for the QS and the CAT system against the buoy's offset from its equilibrium position, whereas the QS restoring force characteristics were designed according to the CAT.…”

Section: Decay Tests In Surgementioning

confidence: 99%

“…The computed buoy motions, the natural periods, and the amount of hydrodynamic damping were compared with experimental measurements. For different mooring models, using quasi-static mooring models coupled with potential flow solvers or viscous flow solvers [20], we found that the hydrodynamic damping of the moored floating structure was generally underpredicted [21].…”

Section: Introductionmentioning

confidence: 97%

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Mooring-Configurations Induced Decay Motions of a Buoy

Jiang

Moctar

Schellin

2021

JMSE

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The hydrodynamic damping of a buoy stationed with three different mooring configurations was estimated using a Navier-Stokes (NS) equations solver coupled with a dynamic mooring model. The mooring configurations comprised a catenary system, a catenary system with sub floaters, and a catenary system with sub floaters and clump weights. Systematic simulations were achieved by adopting the overset grid scheme instead of the conventional morphing grid scheme, which required regenerating the entire mesh when the buoy’s initial position changed, thereby avoiding mesh distortions and numerical instabilities. Motion decay simulations in heave, pitch, and surge were conducted with and without various mooring systems. The analyzed results comprised decaying oscillating motions, natural periods, and associated amounts of damping. The mooring systems influenced not only restoring force characteristics, but also total damping of the moored buoy, which demonstrated the importance of considering mooring-induced damping when investigating moored offshore structures.

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Section: The Viscous Flow Solvermentioning

confidence: 75%

Section: Decay Tests In Surgementioning

confidence: 99%

Section: Introductionmentioning

confidence: 97%

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Mooring-Configurations Induced Decay Motions of a Buoy

Jiang

Moctar

Schellin

2021

JMSE

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“…It is evident that heave motions are hardly affected by the added damper. When a floating structure is moored with a soft mooring system, heave motions are generally dominated by its hydrostatic stiffness and inertia [20]. However, significant discrepancies are evidenced in the pitch motions between the flexible joint without rotational damping and the one with rotational damping, as illustrated in Fig.…”

Section: Resultsmentioning

confidence: 99%

Effect of a rotational damper on a moored and articulated multibody offshore system in waves

Zhang,

Moctar,

Jiang

2023

IOP Conf. Ser.: Mater. Sci. Eng.

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Motions and loads of an articulated and moored floating platform consisting of multiple bodies in waves are investigated through numerical analysis. The wave–structure interaction (WSI) problem is solved using a high-fidelity viscous–flow solver that couples nonlinear rigid body motions, multibody interactions with an internal connection, and mooring dynamics. The study focuses on two modular floating structures (MFSs) connected by a flexible joint, with and without a rotational damper, and positioned using four symmetrical mooring lines. Multibody responses and the corresponding loads acting on the mooring lines and hinged joints are analyzed. Our results reveal that the influence of the damper on heave motions is less significant. Notably, the presence of the rotational damper has a noticeable impact on pitch motions between the two hinged MFSs. Introducing a rotational damper on the flexible joint effectively dampens the highly dynamic pitch motions while not imposing additional loads on the flexible joints.

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“…MoorDyn is a lumpedmass model that has been successfully validated against wave tank measurements by coupling it to a potential flow solver (Hall and Goupee 2015), to a meshless smoothed particle hydrodynamics (SPH) approach (Domínguez et al 2019), and to a mesh-based viscous flow method (Jiang et al 2020a), respectively. The benefits of the coupled mooringviscous flow solver for solving highly nonlinear rigid-body motions interacting with its mooring dynamics were demonstrated by comparing it to a coupled mooring-potential flow solver (Jiang et al 2020a), and to a coupled quasi-static mooring-viscous flow solver (Jiang et al 2020b). In addition, the implemented mooring model supports various mooring configurations by adding floaters and/or clump-weights on the mooring lines (Vissio et al 2015;Hall 2020;Jiang et al 2020cJiang et al , 2021, as exemplarily shown in Fig.…”

Section: Introductionmentioning

confidence: 99%

Extension of a coupled mooring–viscous flow solver to account for mooring–joint–multibody interaction in waves

Jiang

Moctar

2022

J. Ocean Eng. Mar. Energy

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To account for nonlinear wave–structure interaction, mooring dynamics and the associated viscous flow effects, a coupled mooring–viscous flow solver was formerly developed and validated (Jiang et al. in Mar Struct 72:783, 2020a, Validation of a dynamic mooring model coupled with a RANS solver). This paper presents an extension of the coupled mooring–viscous flow solver to solve mooring dynamics interacting with an articulated multibody offshore system. The presently extended solver is verified by comparing the predicted motions of and loads on a moored floating box to those obtained from the formerly validated solver, which was aimed for solving mooring dynamics interacting with a single floating body. The almost identical results obtained from both solvers verify the presently developed multi-module coupling technique for solving the mooring dynamics and articulated multibody dynamics in a coupled manner. Apart from the code comparison and verification, the numerical predictions are also validated against experimental tank measurements both for a single body and an articulated multibody. The good agreements between the numerical predictions and the experimental measurements validate the presently extended solver, where wave-induced body motions together with loads acting on mooring lines and joint connections were examined. Developed as an open-source tool, the extended solver shows a potential of the coupled methodology for analyzing an articulated multibody offshore system, moored with various mooring configurations in extreme sea states, which goes beyond the state of the art.

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Comparative study of mathematical models for mooring systems coupled with CFD

Cited by 11 publications

References 14 publications

Mooring-Configurations Induced Decay Motions of a Buoy

Mooring-Configurations Induced Decay Motions of a Buoy

Effect of a rotational damper on a moored and articulated multibody offshore system in waves

Extension of a coupled mooring–viscous flow solver to account for mooring–joint–multibody interaction in waves

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