Numerical Investigation on the Cage-to-Cage Wake Effect: A Case Study of a 4 × 2 Cage Array

2021 ◽  
Vol 143 (5) ◽  
Author(s):  
Jaesub Sim ◽  
Hui Cheng ◽  
Karl Gunnar Aarsæther ◽  
Lin Li ◽  
Muk Chen Ong
Keyword(s):  
Drag Force ◽  
Fish Farm ◽  
Fish Farms ◽  
Wake Effect ◽  
Cage System ◽  
Flow Interactions ◽  
Wake Effects ◽  
Fish Cages ◽  
Cage Fish

Abstract Aquaculture has been the world’s fastest-growing food producing method and grown to become the second-largest export industry in Norway during the past 40 years. Usually, the high-value fish such as Atlantic Salmon (Salmo Salar) is raised in a multi-cage fish farm, where the flow interactions between fish cages exist. In this study, the interactions between fish cages are implemented into the numerical program, FhSim, to investigate its influences on the responses of a multi-cage fish farm. Tensions in anchor lines, drag force, and cultivation volume of each cage in a full-scale 4 × 2 multi-cage fish farms under different flow directions are analyzed numerically. The discrepancies of the responses based on three cases, i.e., (i) without any wake effects, (ii) with only cage-to-cage wake effect, and (iii) with all the wake effects, are compared and discussed. The results indicate that neglecting the wake effects will overestimate the total drag force of the eight cages up to 128% and underestimate the total cultivation volume of the eight cages as much as 42%. This study can provide suggestions on how to consider the wake effects during the design of the multiple-cage system.

Enhancement of Design Criteria for Fish Farm Facilities Including Operations

2005 ◽  
Author(s):  
Are Johan Berstad ◽  
Harald Tronstad ◽  
Stein-Arne Sivertsen ◽  
Endre Leite
Keyword(s):  
Research Work ◽  
Fish Farming ◽  
Fish Farm ◽  
Design Criteria ◽  
Mooring System ◽  
Fish Farms ◽  
Safety Level ◽  
Operational Conditions ◽  
Farming Industry

A Norwegian Standard NS 9415 (NAS, 2003) has been introduced to the offshore fish farming industry in Norway. This is the first standard dealing with offshore fish farm facilities. The main objective of the standard is to reduce environmental pollution by fish escape. The work process leading to NS 9415 revealed the need for research work in several areas to enhance design criteria with the objective of having a consistent safety level through out the life cycle of a fish farm facility. This paper presents results from a government supported research project with the objective of enhancing criteria for design and operation of fish farm facilities. A case study of a fish farm facility representative for the majority of polyethylene based fish farms in Norway is presented and the sensitivity of such fish farms to variation in the mooring system is shown and discussed for design relevance. The sensitivity of net cage volume to current and weights is presented and discussed. Possible hazards from operational conditions are listed.

Model Testing of Fish Farms for Validation of Analysis Programs

2014 ◽  
Author(s):  
Are Johan Berstad ◽  
Line Fludal Heimstad ◽  
Jørgen Walaunet
Keyword(s):  
Numerical Analysis ◽  
Structural Integrity ◽  
State Of The Art ◽  
Scale Model ◽  
Analysis Tool ◽  
Fish Farms ◽  
Model Experiments ◽  
Cage System ◽  
Aquaculture Industry

This paper presents a case study where results from numerical analysis have been compared to model experiments, performed on a 1/16 scale model. The tested model is a circular cage system with a polyethylene cage. The system is tested both in waves and current. Numerical analysis to document the structural integrity of the fish farms are now a requirement. The state of the art analysis tool used in the aquaculture industry is AquaSim [1]. Results from model experiments are compared to numerical analysis carried out in AquaSim. Uncertainties in the model experiments are investigated and discussed. The differences between the experimental and numerical results are in the same range as the uncertainties.

Numerical Analysis of a Vessel-Shaped Offshore Fish Farm

2018 ◽  
Vol 140 (4) ◽  
Author(s):  
Lin Li ◽  
Zhiyu Jiang ◽  
Andreas Vangdal Høiland ◽  
Muk Chen Ong
Keyword(s):  
Wind Waves ◽  
Single Point ◽  
Fish Farm ◽  
Mooring Line ◽  
Mooring System ◽  
Wave Loads ◽  
Fish Farms ◽  
Mooring Lines ◽  
Environmental Loads ◽  
Fish Cages

The aquaculture industry is aiming to move fish farms from nearshore areas to open seas because of many attractive advantages in the open water. However, one major challenge is to design the structure to withstand the environmental loads due to wind, waves, and currents. The purpose of this paper is to study a vessel-shaped fish farm concept for open sea applications. The structure includes a vessel-shaped hull, a mooring system, and fish cages. The shape of the hull minimizes the wave loads coming from the bow, and the single-point mooring system is connected to the turret at the vessel bow. Such a system allows the whole fish farm to rotate freely about the turret, reduces the environmental loads on the structure and increases the spread area of fish wastes. A basic geometry of the vessel hull was considered and the hydrodynamic properties were obtained from the frequency-domain (FD) analysis. A mooring system with six mooring lines was designed to avoid possible interactions with the fish cages. Time-domain (TD) simulations were performed by coupling the hull with the mooring system. A simplified rigid model of the fish cages was considered. The global responses of the system and the mooring line loads were compared under various wave and current conditions. The effects due to misalignment of wave and current directions on the responses were discussed. Finally, the responses using flexible and rigid net models were compared under steady current conditions.

A Preliminary Study of a Vessel-Shaped Offshore Fish Farm Concept

2017 ◽  
Author(s):  
Lin Li ◽  
Zhiyu Jiang ◽  
Muk Chen Ong
Keyword(s):  
Wind Waves ◽  
Single Point ◽  
Open Water ◽  
Fish Farm ◽  
Mooring Line ◽  
Mooring System ◽  
Wave Loads ◽  
Fish Farms ◽  
Environmental Loads ◽  
Fish Cages

The aquaculture industry is aiming to move fish farms from near-shore area to open seas because of many attractive advantages in the open water. However, one major challenge is to design the structure to withstand the environmental loads due to wind, waves and current. The purpose of this paper is to study a vessel-shaped fish farm concept for open sea applications. The structure includes a vessel-shaped hull, a mooring system and fish cages. The shape of the hull minimizes the wave loads coming from the bow, and the single-point mooring system is connected to the turret at the vessel bow. Such a system allows the whole fish farm to rotate freely about the turret, reduces the environmental loads on the structure and increases the spread area of fish wastes. A basic geometry of the vessel hull was considered and the hydrodynamic properties were obtained from frequency domain analysis. A preliminary mooring system was designed to avoid possible interactions with the fish cages. Time domain simulations were performed by coupling the hull with the mooring system. A simplified rigid model of the fish cages was considered. The global responses of the system and the mooring line loads were compared in various waves and current conditions. The effects due to misalignment of waves and current directions on the responses were also studied.

scholarly journals Development of a Hydropower Turbine Using Seawater from a Fish Farm

Processes ◽  
2021 ◽  
Vol 9 (2) ◽  
pp. 266
Author(s):  
Md Rakibuzzaman ◽  
Sang-Ho Suh ◽  
Hyoung-Ho Kim ◽  
Youngtae Ryu ◽  
Kyung Yup Kim
Keyword(s):  
Power Plants ◽  
Guide Vane ◽  
Cross Flow ◽  
Synchronous Generator ◽  
Fish Farm ◽  
Hydropower Plant ◽  
Fish Farms ◽  
Data Simulation ◽  
Small Hydropower ◽  
Hydropower Plants

Discharge water from fish farms is a clean, renewable, and abundant energy source that has been used to obtain renewable energy via small hydropower plants. Small hydropower plants may be installed at offshore fish farms where suitable water is obtained throughout the year. It is necessary to meet the challenges of developing small hydropower systems, including sustainability and turbine efficiency. The main objective of this study was to investigate the possibility of constructing a small hydropower plant and develop 100 kW class propeller-type turbines in a fish farm with a permanent magnet synchronous generator (PMSG). The turbine was optimized using a computer simulation, and an experiment was conducted to obtain performance data. Simulation results were then validated with experimental results. Results revealed that streamlining the designed shape of the guide vane reduced the flow separation and improved the efficiency of the turbine. Optimizing the shape of the runner vane decreased the flow rate, reducing the water power and increasing the efficiency by about 5.57%. Also, results revealed that tubular or cross-flow turbines could be suitable for use in fish farm power plants, and the generator used should be waterproofed to avoid exposure to seawater.

Interference of cage fish farm on diet, condition factor and numeric abundance on wild fish in a Neotropical reservoir

Aquaculture ◽  
2013 ◽  
Vol 414-415 ◽  
pp. 56-62 ◽  
Author(s):  
Igor P. Ramos ◽  
Heleno Brandão ◽  
Augusto S. Zanatta ◽  
Érica de O.P. Zica ◽  
Reinaldo J. da Silva ◽  
...  
Keyword(s):  
Condition Factor ◽  
Fish Farm ◽  
Wild Fish ◽  
Cage Fish

Feasibility of Repurposing Offshore Decommissioned Gas Rigs into Fish Farms

2021 ◽  
Author(s):  
Saptarshi Pal ◽  
Chengi Kuo
Keyword(s):  
North Sea ◽  
Net Present Value ◽  
Cost Benefit Analysis ◽  
Storage System ◽  
Artificial Reef ◽  
Cost Benefit ◽  
Fish Farm ◽  
Fish Feed ◽  
Offshore Platforms ◽  
Fish Farms

Abstract In the past 70 years the world has relied extensively for its energy needs based on hydrocarbons produced significantly offshore. In recent years many installations with fixed platforms and pipelines are reaching the end of their useful life and are required by law to be decommissioned and removed if an approved alternative use cannot be found. This process coincides with focus on decarbonization arising from global warming and climate change. The conventional way of decommissioning is to remove the structure and take it onshore for disposal. Such an activity costs around £28 million for smaller UKCS installations in the Southern North Sea. Possible alternative solutions include their use as a research-leisure complex and artificial reef. Such an approach would have less impact on the environment and it is therefore worthwhile to explore the feasibility of repurposing these decommissioned UKCS platforms. The paper begins by highlighting the background to UKCS offshore decommissioning and farming fish life-cycle. This is followed by a critical review of the three options of total and partial removals and leave-on-site. It is found that repurposing decommissioned platforms for aquaculture farm has not been given sufficient attention and thus offers scope for a project to explore the feasibility of such a solution. Existing offshore fish farming in various countries are examined before using a decision-making matrix to select the most suitable UKCS installation for conversion and this led to using a normally unattended gas platform for the case study. The focus for this paper is on design and operation of an unattended fish farm and its cost benefit analysis. The former covers fish cage selection, capacity calculation, fish handling procedures, fish feed characteristics, feed demand, designing feed logistics and storage system. The processing facilities are layout on two decks and power needs are generated using a hybrid system of diesel and Li-ion battery. The possibility of using renewable sources by connecting to wind energy grids was also considered. For the latter capital and operating expenditure, revenue generated and maintenance costs are estimated before performing net present value prediction of the profitability of the fish farm over 10 years with for example up to 8 cages and three discount rates. The main conclusions derived are: It is technically feasible to convert a decommissioned gas platform to a fish farm and the operation can be economic. However, liability transfer implications in a repurposed offshore decommissioned gas platforms to fish farms were not established to verify the project viability. The conversion of unattended offshore gas platforms in the UKCS to an automated offshore fish farm is a novel solution which has not been implemented in the North Sea before. The work will provide an economic and environmental friendly solution to decommissioning offshore platforms and provide with a possible profitable investment.

scholarly journals Predicting the Heading Misalignment of a Vessel-Shaped Offshore Fish Farm Under Waves and Currents

2018 ◽  
Author(s):  
Lin Li ◽  
Zhiyu Jiang ◽  
Jungao Wang ◽  
Muk Chen Ong
Keyword(s):  
Reference Site ◽  
Single Point ◽  
Fish Farm ◽  
Misalignment Angle ◽  
Integrated Method ◽  
Open Sea ◽  
Waves And Currents ◽  
Spread Area ◽  
Fish Cages ◽  
Current Reduction

A vessel-shaped fish farm concept for open sea applications has been proposed recently. The whole system consists of a vessel-shaped floater, fish cages positioned longitudinally along the floater, and a single-point mooring system. The whole system weathervanes; this feature increases the spread area for the fish waste. However, the downstream cages may experience reduced water exchange when the vessel is parallel to the currents. This situation may jeopardize the fish health. A dynamic positioning (DP) system may be necessary to improve the flow conditions. This paper investigates the misalignment angle between the heading of the vessel-shaped fish farm and the currents under combined wave and current conditions. The misalignment angle is critical for the estimation of the DP system consumption. A numerical model of the fish farm system with flexible nets is developed. Current reduction factors are included to account for the flow velocity reductions between the net panels. The heading of the system is obtained by finding the equilibrium condition of the whole system under each combined wave and current condition. An integrated method using metamodels is proposed and applied for the prediction of the misalignment angle for a reference site. The probability distribution of the misalignment angle between the vessel heading and the currents is calculated using the Kriging metamodel for the reference site. Based on the prediction, the requirement for the DP system to improve the flow condition in the fish cages is discussed.

The Effects of Fish Cages on Ambient Currents

2011 ◽  
Vol 134 (1) ◽  
Author(s):  
Lars C. Gansel ◽  
Thomas A. McClimans ◽  
Dag Myrhaug
Keyword(s):  
Drag Force ◽  
Particle Image ◽  
Reynolds Numbers ◽  
Strain Gauges ◽  
Metal Mesh ◽  
Image Velocimetry ◽  
Flow Through ◽  
Fish Cages ◽  
Ambient Currents ◽  
Wake Characteristics

Experiments were carried out to measure forces on and wake characteristics downstream from fish cages. Cylinders made from metal mesh with porosities of 0%, 30%, 60%, 75%, 82%, and 90% were tested in a towing tank. The drag force was measured with strain gauges, and the flow field downstream from the models was analyzed using particle image velocimetry. The Reynolds numbers ranged from 1000–20,000 based on the model diameter and 15–300 based on the diameter of the strings of the mesh as an independent obstacle. High porosities (here, 82% and 90%) lead to low water blockage and allow a substantial amount of water to flow through the model. The data indicate that the wake characteristics change toward the wake characteristics of a solid cylinder at a porosity just below 75%. The drag force is highly dependent on the porosity for high porosities of a cylinder.

scholarly journals STUDY, DESIGN AND SIMULATION OF A PROGRAM FOR NUMERICAL EVALUATION OF VEHICLES’ FUEL CONSUMPTION DUE TO DRAG FORCE; CASE OF LIGHT VEHICLES.

2020 ◽  
Vol 7 (1) ◽  
pp. 1-11
Author(s):  
Mbelle Samuel Bisong ◽  
Paune Felix ◽  
Lokoue D. Romaric Brandon ◽  
Pierre Kisito Talla
Keyword(s):  
Mathematical Model ◽  
Computer Program ◽  
Fuel Consumption ◽  
Drag Force ◽  
Numerical Evaluation ◽  
Construction Companies ◽  
Mathematical Relation ◽  
Basic Equations ◽  
Valid Information

Nowadays, vehicles are being abandoned by their users due to their high fuel consumption which had not been studied by the user from the start. Thus, the need to study the fuel consumption of vehicles due to one of the factors which greatly affects it; drag force, so as to produce information which vehicle users can have before purchasing their vehicles. With regards to this, this work is focused on the development of a computer program able to evaluate the fuel consumption of light vehicles. To achieve this, the basic equations of consumption are used to arrive at a mathematical relation between drag force and fuel consumption. This mathematical model is further implemented on the analytical software Matlab in order to produce the various consumption curves of the vehicles case study. A simulator which takes into consideration a vehicle’s engine data in order to produce specific consumption curves and provide valid information on the fuel consumption of the vehicle is developed from this mathematical model. It can be used in automotive construction companies and also by any individual.

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