Journal of Marine Science and Engineering

Research

14 pages, 4003 KiB

Open AccessArticle

Experimental and Numerical Investigation on the Motion Responses of a Spar-Type Floating Structure with Aquaculture Feeding Systems

by Qiao Li, Shenyi Bai, Shuchuang Dong, Jinxin Zhou and Daisuke Kitazawa

J. Mar. Sci. Eng. 2024, 12(8), 1329; https://doi.org/10.3390/jmse12081329 - 6 Aug 2024

Viewed by 519

Abstract

The combination of aquaculture industry with floating offshore wind turbines has the potential to generate significant economic advantages for both industries. To investigate this potential, the present study focuses on analyzing the heave, and pitch dynamic responses of a Spar-type floating offshore wind [...] Read more.

The combination of aquaculture industry with floating offshore wind turbines has the potential to generate significant economic advantages for both industries. To investigate this potential, the present study focuses on analyzing the heave, and pitch dynamic responses of a Spar-type floating offshore wind turbine that incorporates an aquaculture feeding system. A series of water tank model tests, together with numerical calculations, were conducted using a 1/56 scale model of a 2 MW, displacement 3500 tons, floating Spar-type wind turbine. The feeding system was placed inside the Spar and slightly above the waterline by adjusting the configuration of the total weight. The weight of the feeding system in the experiments is 100 tons, capable of sustaining 300 tons of fish for an entire week, and the realistic applications have been expanded using the numerical calculation. For this reason, the present study serves a good case study for general understanding, because the integration of the feeding system inevitably raises the center of gravity of the structure and potentially affects its overall stability. The experiments revealed no discernible increase in the heave motion. Moreover, the pitch motion theoretically increased, but occasionally decreased in the experiments with the overall inclination angles being less than 1.2 degrees during the experiments. As a result, the present study supports the practice of integrating a Spar-type wind turbine with feeding systems. Future research should continue to comprehensively examine, both experimentally and numerically, the motion responses of the wind turbine and aquaculture facilities with varying configurations. Full article

(This article belongs to the Special Issue Next-Generation Sustainable Marine Fisheries and Aquaculture Engineering)

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26 pages, 11060 KiB

Open AccessArticle

Numerical Investigation on Mooring Line Configurations of a Semisubmersible Fish Farm for Global Performance

by Mingjia Chen, Liuyi Huang, Hui Cheng and Qianli Wu

J. Mar. Sci. Eng. 2024, 12(6), 880; https://doi.org/10.3390/jmse12060880 - 25 May 2024

Viewed by 609

Abstract

The growth of the aquaculture industry has led to the development of innovative fish farming technologies, such as semisubmersible fish farms which offer significant advantages in terms of scalability and environmental sustainability. The study utilizes a new workflow based on an open-source finite [...] Read more.

The growth of the aquaculture industry has led to the development of innovative fish farming technologies, such as semisubmersible fish farms which offer significant advantages in terms of scalability and environmental sustainability. The study utilizes a new workflow based on an open-source finite element solver, Code_Aster, to calculate the hydrodynamic dynamic response of a fish farm. The mooring line configuration of a semisubmersible fish farm plays a crucial role in ensuring its stability and overall performance. This study presents a comprehensive numerical investigation aimed at evaluating the influence of different mooring line configurations (i.e., 4 × 1, 4 × 2, and 4 × 3) on the global performance of a semisubmersible fish farm under regular waves and irregular waves conditions. Increasing the number of mooring lines can reduce the mean and extreme tension in individual mooring lines and suppress the horizontal motions, but bring neglectable effects on the rotational responses. The findings from this research provide valuable insights into the optimal mooring line configuration for the global performance of semisubmersible fish farms. Full article

(This article belongs to the Special Issue Next-Generation Sustainable Marine Fisheries and Aquaculture Engineering)

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16 pages, 18557 KiB

Open AccessArticle

Water-Tank and Semi-Field Experimental Investigation of a Hose Net Fish-Hauling Device for Next-Generation Set-Net Fishing

by Qiao Li, Shuchuang Dong, Daigo Furuichi, Yoichi Mizukami and Daisuke Kitazawa

J. Mar. Sci. Eng. 2024, 12(1), 44; https://doi.org/10.3390/jmse12010044 - 23 Dec 2023

Viewed by 991

Abstract

The flexible fire hose and net (hose net) is a novel fish-hauling device developed for set-net fishery. The hose net is placed inside the box chamber net, air is injected from one edge of the hose net, the hoses are inflated, and the [...] Read more.

The flexible fire hose and net (hose net) is a novel fish-hauling device developed for set-net fishery. The hose net is placed inside the box chamber net, air is injected from one edge of the hose net, the hoses are inflated, and the buoyancy force is increased. The net floats up gradually, cornering the fish on the other edge. In previous studies, we have conducted a series of floating-up and sinking-down experiments to evaluate the performance of the hose net in calm water. In this study, aimed at the practical implementation of the hose net fish-hauling system, we conducted a water tank experiment and a semi-field test to confirm the operation of the hose net, which was installed inside a box chamber net model. The results demonstrated that the net could float up gradually in an ideal form and stretched on the surface of the box net. The time taken to float up processes varied with the air injected into the auxiliary hose and hose net, so that the motion of the hose net could be controlled by adjusting the air at different parts of practical operation. Furthermore, semi-field trials were conducted to verify its performance in the natural marine environment and its ability to capture schools of fish. Overall, this innovative hose net fish-hauling device is expected to be valuable for next-generation set-net fishing. Full article

(This article belongs to the Special Issue Next-Generation Sustainable Marine Fisheries and Aquaculture Engineering)

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19 pages, 3734 KiB

Open AccessArticle

Hydrodynamic and Structural Optimization of a Truss-Floating Aquaculture Vessel

by Yuchen Zhang, Ji Zhang, Changqing Jiang, Zhaode Zhang, Peng Xu and Yuan Zhang

J. Mar. Sci. Eng. 2023, 11(12), 2385; https://doi.org/10.3390/jmse11122385 - 18 Dec 2023

Cited by 1 | Viewed by 969

Abstract

A truss-floating aquaculture vessel is an innovative addition to the aquaculture industry, characterized by its large, porous, ship-shaped structure. It differs from traditional ships, offshore structures, and individual net cages. Due to its distinctive features, a large-scale truss-floating aquaculture vessel requires dedicated hydrodynamic [...] Read more.

A truss-floating aquaculture vessel is an innovative addition to the aquaculture industry, characterized by its large, porous, ship-shaped structure. It differs from traditional ships, offshore structures, and individual net cages. Due to its distinctive features, a large-scale truss-floating aquaculture vessel requires dedicated hydrodynamic and structural analysis, which is the primary focus of this paper. Our study starts with the calculation of wave loads acting on the vessel using the equivalent design wave method. Subsequently, it delves into the analysis of structural characteristics and stress distribution of the truss-floating aquaculture vessel, upon which structural optimization is performed. To determine the optimal design variables, a sensitivity analysis of the truss members is carried out using a parametric research method. Finally, the structure with multiple objectives is optimized using two distinct approaches: the adaptive simulated annealing algorithm (ASA) and the multi-island genetic algorithm (MIGA). The results reveal that prior to optimization, there is a risk of buckling and yielding damage occurring at various connections within the vessel structure. After optimization, the structural strength is significantly improved, accompanied by a reduction in the total weight of the vessel. This study offers a valuable reference for the design and structural safety assessment of this innovative truss-floating tank-type aquaculture vessel. Full article

(This article belongs to the Special Issue Next-Generation Sustainable Marine Fisheries and Aquaculture Engineering)

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12 pages, 2773 KiB

Open AccessArticle

The Escape Intensity and Its Influencing Factors in Antarctic Krill (Euphausia superba) Passing through Large Mesh at the Front End of a Commercial Trawl

by Zhongqiu Wang, Lumin Wang, Yongjin Wang, Hao Tang and Liuxiong Xu

J. Mar. Sci. Eng. 2023, 11(12), 2370; https://doi.org/10.3390/jmse11122370 - 15 Dec 2023

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Abstract

The purpose of this study was to comprehend the escape intensity and its influencing factors in Antarctic krill (Euphausia superba) that escaped through large mesh located at the front end of commercial trawl nets. Two pocket nets were employed to collect [...] Read more.

The purpose of this study was to comprehend the escape intensity and its influencing factors in Antarctic krill (Euphausia superba) that escaped through large mesh located at the front end of commercial trawl nets. Two pocket nets were employed to collect escaped krill that passed through the mesh opening in the first section (400 mm mesh size, without liner) and second section (16 mm mesh size liner) of the trawl body. The results show that krill escape primarily took place in the first section of the trawl body. Meanwhile, there was almost no krill escape observed in the second section of the trawl body, primarily attributable to the presence of a 16 mm mesh size liner. In terms of body length composition, the average PSI (percentage similarity index) was 67.31 (95% CI: 61.86–72.87) for krill from the pocket net on the larger mesh part and the codend. In addition, the PSI was significantly different (p < 0.05) between the day (60.96, 95% CI: 55.68–66.71) and night (83.62, 95% CI: 76.80–89.46). The escape intensity of krill ranged from 20.83 to 213.13 g·m⁻² per ton per hour in the area at the front end of trawl body, with a mean value of 76.52 (95% CI: 55.22–101.09) g·m⁻² per ton per hour during the daytime, and 144.66 (95% CI: 110.44–180.03) g·m⁻² per ton per hour at night. These results indicate that krill can see and avoid contacting the netting easily during the day, particularly for larger individuals. This provides insight into the design of krill trawls, specifically on the arrangement of liners, which should be integrated from the front part of the trawl body. Full article

(This article belongs to the Special Issue Next-Generation Sustainable Marine Fisheries and Aquaculture Engineering)

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14 pages, 4417 KiB

Open AccessArticle

Sinking Behavior of Netting Panels Made with Various Twine Materials, Solidity Ratios, Knot Types, and Leadline Weights in Flume Tank

by Chenxu Shan, Hao Tang, Nyatchouba Nsangue Bruno Thierry, Wei Liu, Feng Zhang, Meixi Zhu, Can Zhang, Liuxiong Xu and Fuxiang Hu

J. Mar. Sci. Eng. 2023, 11(10), 1972; https://doi.org/10.3390/jmse11101972 - 12 Oct 2023

Viewed by 1310

Abstract

Netting is an important component of fishing gear design, and its ability to sink determines the effectiveness of fishing gears such as purse seines, falling nets, and stick-held nets. Therefore, it is crucial to thoroughly investigate the sinking parameters (sinking depth and sinking [...] Read more.

Netting is an important component of fishing gear design, and its ability to sink determines the effectiveness of fishing gears such as purse seines, falling nets, and stick-held nets. Therefore, it is crucial to thoroughly investigate the sinking parameters (sinking depth and sinking speed) of the netting panel as a function of the leadline weights using various twine materials, knot types, and solidity ratios. In this study, a generalized additive model (GAM) was utilized to analyze the impact of each factor on the sinking performances of the netting. The results revealed that the sinking depth of the netting was positively correlated with sinking time and leadline weight. However, the netting featured a maximum sinking depth limit, indicating that the sinking depth would not increase beyond a leadline weight of 69.5 g. During the initial phase of the sinking process, the sinking velocity of each netting panel initially increased but gradually decreased over time. The incorporation of a leadline weight reduced sinking time. Thereby, polyester netting exhibited the shortest average sinking time. A comparison of netting types with similar solidity ratios showed that the maximum sinking depth of the nylon netting was 13.20% and 10.11% greater than that of polyethylene and polyester nettings, respectively. In addition, nylon nets’ time average sinking speed was 64.58% and 4.62% greater than that of polyethylene and polyester nettings, respectively. The analysis of the GAM model clearly showed that the leadline weight has a significant effect on the netting sinking speed and depth. To ensure that the netting can reach its maximum sinking speed, it is strongly recommended to use nylon and polyester nettings with a low solidity ratio, i.e., a lower twine diameter and greater mesh size with a higher leadline weight, when constructing fishing gear such as purse seines with higher net leadline weights. Full article

(This article belongs to the Special Issue Next-Generation Sustainable Marine Fisheries and Aquaculture Engineering)

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20 pages, 4352 KiB

Open AccessArticle

Flow Field Pattern and Hydrodynamic Characteristics of a Grid Device Made with Various Grid Bar Spacings at Different Inclination Angles

by Can Zhang, Hao Tang, Nyatchouba Nsangue Bruno Thierry, Liqiang Yin, Feng Zhang, Meixi Zhu, Chenxu Shan, Liuxiong Xu and Fuxiang Hu

J. Mar. Sci. Eng. 2023, 11(10), 1966; https://doi.org/10.3390/jmse11101966 - 11 Oct 2023

Cited by 1 | Viewed by 1027

Abstract

The grid is a crucial component in constructing grid-type bycatch reduction devices. The grid’s structural characteristics and orientation significantly impact the hydrodynamic characteristics and efficacy of the separation device. Therefore, it is essential to thoroughly understand the grid device’s hydrodynamic characteristics and flow [...] Read more.

The grid is a crucial component in constructing grid-type bycatch reduction devices. The grid’s structural characteristics and orientation significantly impact the hydrodynamic characteristics and efficacy of the separation device. Therefore, it is essential to thoroughly understand the grid device’s hydrodynamic characteristics and flow field to optimize its structure. Thus, this study used CFD numerical simulation and flume tank experiments to investigate the effects of inclination grid angles and grid bar spacing on hydrodynamic forces and flow fields around a circular grid. The results indicated that the hydrodynamic forces acting on the circular grid increased with higher flow velocity and inclination grid angle, decreasing with smaller grid bar spacing. Flow velocity acceleration zones were observed at the upper and lower ends of the grid and between the grid bars. Additionally, upwelling and vortices were present at the back of the grid. It was found that an increase in the inclination grid angle accelerated the vortex and wake effects. Full article

(This article belongs to the Special Issue Next-Generation Sustainable Marine Fisheries and Aquaculture Engineering)

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18 pages, 6123 KiB

Open AccessArticle

Time–Frequency Analysis of Nonlinear Dynamics of an Aquaculture Cage Array in Waves

by Liu Zhu, Yuan Cheng, Jinfang Wang, Hongyu Zhu and Zhijing Xu

J. Mar. Sci. Eng. 2023, 11(9), 1818; https://doi.org/10.3390/jmse11091818 - 18 Sep 2023

Viewed by 991

Abstract

The nonlinear dynamic response of an aquaculture cage array caused by wave-frequency and low-frequency excitations coupled with the nonlinearity of the mooring and the netting system is a complicated problem. So far, this problem still has not been completely understood. To address this [...] Read more.

The nonlinear dynamic response of an aquaculture cage array caused by wave-frequency and low-frequency excitations coupled with the nonlinearity of the mooring and the netting system is a complicated problem. So far, this problem still has not been completely understood. To address this issue, we consider the nonlinear interaction of an extreme wave with an aquaculture cage array containing 16 net cages in a 2 × 8 configuration. This paper aims to provide insight into understanding the nonlinear dynamics of an aquaculture cage array via time–frequency analysis. Time-domain analysis shows that the cage array exhibits weak nonlinearity in the surge and heave motions. On the contrary, there is strong nonlinearity in the sway motion under 45

°

and 90

°

wave attacks. Aside from this, the frequency-domain analysis indicates that nonlinearities exist in all three of these different responses (surge/sway/heave). Particularly, the low-frequency component has a predominant effect on the nonlinearity of the sway motion under 45

°

and 90

°

wave attacks. With this understanding, future aquaculture fish farms that contain multiple cages (i.e., cage array) can be potentially designed to withstand severe conditions in the open ocean. Full article

(This article belongs to the Special Issue Next-Generation Sustainable Marine Fisheries and Aquaculture Engineering)

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