Hydrodynamic Sensitivity of Moored and Articulated Multibody Offshore Structures in Waves

Changqing Jiang,Thomas E Schellin,Ould El Moctar

doi:10.3390/jmse9091028

Changqing Jiang, Thomas E Schellin + Show 1 more

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https://doi.org/10.3390/jmse9091028

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Abstract

Within the framework of Space@Sea project, an articulated modular floating structure was developed to serve as building blocks for artificial islands. The modularity was one of the key elements, intended to provide the desired flexibility of additional deck space at sea. Consequently, the layout of a modular floating concept may change, depending on its functionality and environmental condition. Employing a potential-flow-based numerical model (i.e., weakly nonlinear Green function solver AQWA), this paper studied the hydrodynamic sensitivity of such multibody structures to the number of modules, to the arrangement of these modules, and to the incident wave angle. Results showed that for most wave frequencies, their hydrodynamic characteristics were similar although the floating platforms consisted of a different number of modules. Only translational horizontal motions, i.e., surge and sway, were sensitive to the incident wave angle. The most critical phenomenon occurred at head seas, where waves traveled perpendicularly to the rotation axes of hinged joints, and the hinge forces were largest. Hydrodynamic characteristics of modules attached behind the forth module hardly changed. The highest mooring line tensions arose at low wave frequencies, and they were caused by second-order mean drift forces. First-order forces acting on the mooring lines were relatively small. Apart from the motion responses and mooring tensions, forces acting on the hinge joints governed the system’s design. The associated results contribute to design of optimal configurations of moored and articulated multibody floating islands.

Highlights

Accepted: 16 September 2021The majority of the world’s population lives in coastal areas where space has always been at a premium because available land space is limited [1]
To design reasonable configurations of such floating islands, we investigated the hydrodynamic sensitivity of hinged multibody structures, the number of modules, the modules’ arrangement, and the incident wave angle, using a weakly nonlinear potential-flow approach
This section starts with the validation of the adopted numerical model using experimentally measured results from Thill [28] and computational fluid dynamics (CFD)

Summary

Introduction

Accepted: 16 September 2021The majority of the world’s population lives in coastal areas where space has always been at a premium because available land space is limited [1]. Waterfronts may reclaim or change the utilization of large parts of existing land spaces as sea levels rise with global warming. With an increasing need for affordable deck space at sea, the concept of a very large offshore floating structure (VLFS) came into being. This structure embodies an effective platform for the development of marine resources. Large oil and gas storage facilities [2], floating airports [3], offshore tourist resorts [4], fish farming factories [5], and marine renewable energy platforms [6] are typical examples. Lamas-Pardo et al [7]

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