Qualifying the design of a floating closed-containment fish farm using computational fluid dynamics

Jagan M.R Gorle,Bendik F Terjesen,Astrid B Holan,Arne Berge,Steven T Summerfelt

doi:10.1016/j.biosystemseng.2018.08.012

Jagan M.R Gorle, Bendik F Terjesen + Show 3 more

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https://doi.org/10.1016/j.biosystemseng.2018.08.012

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Abstract

In order to overcome the environmental consequences of traditional net pens in producing Atlantic salmon, closed containment aquaculture systems are being developed, where the culture volume is separated from the ambient environment by an impermeable wall. However, several challenges in terms of construction and hydrodynamic properties must be solved before such systems can be used on a large scale. A study was thus performed on the design of a floating closed-containment fish farm in sea. This paper presents the design and flow analysis of two versions of the globe; first is the pilot design of a 74 m3 globe, and the second is the design of a 3500 m3 globe for post-smolts of Atlantic salmon. The results of turbulence model of the pilot globe were validated against the velocity measurements using acoustic Doppler velocimetry. Computational assessment of various flow characteristics includes the velocity and vorticity fields. The streamline pattern confirmed the secondary vortices, creating the tea-cup hydrodynamics. Coherent vortices, identified by means of Q-criterion, show the presence of vortex column in the globe. Two inlet configurations were tested on the post-smolt globe for improved performance. Design 1 has the standard one-column nozzle configuration, and the Design 2 has two-column nozzles to create a V-shaped inflow. The mixing action of the two designs was examined using Lagrangian particle tracking. Considerable influence of inlet configuration on the particle motion was observed. It was found that V-nozzles (two columns of inlet nozzles) are more effective than standard nozzles in flushing the solid particles.

Highlights

The production of Atlantic salmon is the paramount activity in Norwegian aquaculture, accounting for more than 80% of the total aquaculture production in the country
This paper presents the development of Computational Fluid Dynamics (CFD) models of a closed-containment aquaculture system
Such aquaculture systems are increasingly being focused on as a technology that can lead to further growth of the salmon farming industry (e.g. Calabrese et al, 2017; Summerfelt et al, 2016)

Summary

Introduction

The production of Atlantic salmon is the paramount activity in Norwegian aquaculture, accounting for more than 80% of the total aquaculture production in the country. Aspiring to increase the salmon production by five times by 2050, Norwegian aquaculture has been evolving with new businesses and innovative technologies with a focus on the environmental performance of fish farms (Hagspiel, Hannevik, Lavrutich, Naustdal, & Struksnæs, 2018; Olafsen, Winther, Olsen, & Skjermo, 2012). There are many challenges facing this proposed five-fold expansion in production, which include sea lice, diseases, production losses etc. This necessitates innovative production systems such as closed-containment systems (CCS), where the fish are separated from the outside environment. With a better control on production, environmental impact and disease transmission makes CCS a promising alternative to open-cage production systems

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