The aquaculture industry has increased rapidly the last 20 years. In almost all fish farms, the fish is held captured in net cages. Net structures are built up with twines as shown in Figure 1. Various parameters of importance for the loads to nets such as solidity, Reynolds number, flow angle relative to mesh and increased flow around twines compared to single twines. This paper outlines such effects. This paper consider loads to net panels considering the net a sum of twines and then sum the forces twine by twine. Based on this approach the paper presents a calculation method for net meshes. The presented load formulation is valid for rectangular and diamond shaped meshes and is valid for any 3D orientation of flow relative to mesh. The presented method for load calculation includes methodology for deriving the forces to a net structure based on knowledge of drag resistance for an individual twine. This methodology is compared with other published formulae and empirical data. A formula is presented based on a twine in wake consideration. The presented formula is compared to measurements for test cases both in terms of a net panel and for a full cage model. Results show good agreement.
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.
As of April 1st 2004 all new marine fish farms in Norway need to be certified to comply with technical criteria in a new Norwegian Standard, NS 9415 (NAS, 2003). This paper gives an overview of the design rules. Marine fish farms have a strongly flexible hydroelastic behavior. The design rules have revealed the need for calculations to verify the structural capacity of such facilities. This paper describes how loads and response are derived on the fish farm structures. In order to account for the large geometrical deflections occurring in fish farm components such as the net and anchor cables which interacts with stiffer structural components, time domain simulations analysis of such facilities is required to assess the structural integrity. This paper report a proposed practical calculation method and results from model tests have been carried out to validate calculations. Good correspondence was shown. Additionally some applications are described.
This paper presents a case study of a structure of a novel fish farm cage. The “AquaTraz” cage is more similar to structures known to the the oil and gas industry. The cage has the same shape as the normal cages used in the aquaculture industry and can be introduced to existing grid-moorings. Model testing has been carried out and results from the model test are compared with results from numerical simulations using the tool AquaSim. The response deviating from classic fish farms is shown and what extra considerations that should be carried out for this type of systems compared to classic fish farms is discussed.
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.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.