Water wave trapping in a long array of bottomless circular cylinders

Chatjigeorgiou, Ioannis K.

doi:10.1016/j.wavemoti.2018.08.003

Cited by 8 publications

(7 citation statements)

References 49 publications

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“…In general, water filled structures can be found in a wide range of applications including Wave Energy Converters (WEC) [3][4][5], Oscillating Water Columns (OWC) [6,7], and energy storage concepts [8,9]. The correct prediction of the motion and forces acting on a floating body are essential for the structural and mooring designs [10,11].…”

Section: Introductionmentioning

confidence: 99%

Comparison of a Floating Cylinder with Solid and Water Ballast

Gabl

Davey

Nixon

et al. 2019

Water

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Modelling and understanding the motion of water filled floating objects is important for a wide range of applications including the behaviour of ships and floating platforms. Previous studies either investigated only small movements or applied a very specific (ship) geometry. The presented experiments are conducted using the simplified geometry of an open topped hollow cylinder ballasted to different displacements. Regular waves are used to excite the floating structure, which exhibits rotation angles of over 20 degrees and a heave motion double that of the wave amplitude. Four different drafts are investigated, each with two different ballast options: with (water) and without (solid) a free surface. The comparison shows a small difference in the body’s three translational motions as well as the rotation around the normal axis to the water surface. Significant differences are observed in the rotation about the wave direction comparable to parametric rolling as seen in ships. The three bigger drafts with free surface switch the dominant global rotation direction from pitch to roll, which can clearly be attributed to the sloshing of the internal water. The presented study provides a new dataset and comparison of varying ballast types on device motions, which may be used for future validation experiments.

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Section: Introductionmentioning

confidence: 99%

Comparison of a Floating Cylinder with Solid and Water Ballast

Gabl

Davey

Nixon

et al. 2019

Water

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“…The first-order (linear) boundary value problem is formulated and solved by utilizing the matched eigenfunction expansion technique, combined with the "direct" solution methodology for the numerical implementation. This semi-analytical approach was developed and described in [10,25]. For making this study self-contained, we briefly present the main aspects of the approach taken in [10,25].…”

Section: Hydrodynamic Modelmentioning

confidence: 99%

“…This semi-analytical approach was developed and described in [10,25]. For making this study self-contained, we briefly present the main aspects of the approach taken in [10,25].…”

Section: Hydrodynamic Modelmentioning

confidence: 99%

“…This, however, requires the expression of the scattered components for j q, in the local coordinate system r q , θ q of the randomly selected cylinder q in the array, rather than in the local system r j , θ j , j q. For this purpose, Graf's addition theorem is employed for the modified Bessel function of the second kind and for the Hankel function of the first kind, in Equation (19) (more details can be found in [10,25]).…”

Section: Hydrodynamic Modelmentioning

confidence: 99%

“…The developed ONP consists of two distinctive numerical components, appropriately coupled in an integrated computational environment. The first one corresponds to a hydrodynamic model (HM), which solves the diffraction problem of the examined multi-body arrangement in the frequency domain in an accurate and computationally efficient manner, by utilizing the matched eigenfunction expansion technique and the "direct" solution methodology for the numerical implementation [10,25]. Accordingly, it calculates the linear heave exciting forces of the cylinders.…”

Section: Introductionmentioning

confidence: 99%

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Wave Exciting Force Maximization of Truncated Cylinders in a Linear Array

2020

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This study focuses on the determination of optimum layout configurations for a linear array of identical mutually interacting truncated cylinders. Optimum configurations correspond to those that maximize either the total heave exciting force acting on all cylinders of the array or the heave exciting force applied on pairs of cylinders within the array. For achieving this goal, we developed and applied an efficient optimization numerical process (ONP), where a robust hydrodynamic numerical model, capable of solving the diffraction problem of the examined multi-body arrangement in the frequency domain, was appropriately coupled with a genetic algorithm solver in an integrated computational environment. Initially, the efficiency of the ONP is demonstrated by comparing results with those of other investigations that resulted from the deployment of classical optimization methods. Then, ONP is applied for a linear array of nine cylinders for determining the optimum layout configurations under the action of the head and perpendicular to the array waves, and for different maximum allowable array lengths. The resulting optimum configurations correspond to a random positioning of the cylinders within the array. Nevertheless, they are characterized by the formation of clusters of closely-positioned cylinders, which induce positive hydrodynamic interactions in terms of maximizing the exciting forces.

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