Multi-directional random wave interaction with an array of cylinders

Abstract

. (2015). Multi-directional random wave interaction with an array of cylinders. Ocean Engineering, 110, 62-77. DOI: 10.1016/j.oceaneng.2015 ABSTRACTBased on the linear theory of wave interaction with an array of circular bottom-mounted vertical cylinders, systematic calculations are made to investigate the effects of the wave directionality on wave loads in short-crested seas. The multi-directional waves are specified using a discrete form of the Mitsuyasu-type spreading function. The time series of multi-directional wave loads, including both the wave run-up and the wave force, can be simulated. The effect of wave directionality on the wave run-up and wave loading on the cylinders is investigated. For multi-directional random waves, as the distribution of wave spreading becomes wider, the wave run-up at some points around the cylinders is found to increase. This suggests that multi-directional wave run-up tends to be larger than unidirectional wave run-up. In addition, the wave directionality has a significant influence on the transverse force. The biggest transverse force is found to occur on the rear cylinder rather than the front one. This is quite different from the results in unidirectional waves and should be paid much more attention in the design of offshore structures. At last, the possibility of the near-trapping under the multi-directional random waves is investigated. It is found that the near-trapping also occurs for multi-directional wave conditions.

CFD Simulation of Ship Seakeeping Performance and Slamming Loads in Bi-Directional Cross Wave

“…Therefore, this paper aims at investigating ship seakeeping behavior in wind-driven bi-directional cross sea waves. Some researchers have investigated the interaction of multi-directional wave with fixing offshore structures [3][4][5]. However, studies on the seakeeping behavior of free running ships or other floating structures in multi-directional wave are quite limited.…”

Advances and Challenges in Wave Energy Park Optimization—A Review

“…Recently, some works have considered the performance and optimization of wave energy arrays in short-crested, or omni-directional, waves. Wave runup and trapped wave modes were studied both experimentally and analytically in an array of bottom-mounted cylinders by Ji et al (2015). The computed and experimentally obtained results agreed well, and it was seen that unidirectional wave modeling would overpredict the normal force and underpredict the transversal force on the cylinders.…”

“…Magagna et al (2011) measured the interaction factor in an array of OWCs experimentally. Trapped modes within an array of eight fixed truncated cylinders were demonstrated experimentally by Wolgamot et al (2016), and near-trapping was also observed in an array of fixed cylinders in short-crested waves by Ji et al (2015). A triangular array of three spar-buoy WECs at a scale of 1:32 was studied experimentally by Correia da Fonseca et al (2016), and it was found that, in wave climates with large energy periods, the array performed better than three isolated devices, i.e., an interaction factor larger than one was observed.…”

“…modes (De Chowdhury and Manasseh, 2017;Wolgamot et al, 2017), interaction distance cut-off (Göteman et al, 2015a), a nearest neighbor approach (Sarkar et al, 2016), and Haskind's relation (Flavià and Clément, 2017) have been introduced. Both the iterative and non-iterative versions of the multiple scattering theory have been further developed and used to model the hydrodynamics of wave energy parks (Ji et al, 2015;Konispoliatis and Mavrakos, 2016;Göteman, 2017;Ruiz et al, 2017;Fang et al, 2018;Giassi and Göteman, 2018;Zheng et al, 2018Zheng et al, , 2019Liu et al, 2019). Several other analytical methods have been developed and used for wave energy park applications, including matched asymptotic expansions (McIver and Evans, 1988), multipole expansions (Linton and Evans, 1993), and Bragg scattering (Li and Mei, 2007).…”

“…With the physical experiments of wave energy parks carried out in the past few years, validation of analytical or numerical modeling methods has become possible. An analytical multiple scattering method was compared to experimental data for an array of bottom-mounted cylinders in short-crested waves by Ji et al (2015), and the agreement on wave run-up was generally good, but the computations underpredicted the wave forces. Simulations using BEM software and analytical methods were compared to experimental data for five WaveStar models at a scale of 1:20 by Mercadé Ruiz et al (2017).…”