Design and Model Testing of Aquaculture Net-Pens

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Project Type: 
Research
Project Number: 
R/FMD-506
Inception Date: 
1995
Completion Date: 
1997
Theme Area: 
Sustainable Aquaculture

Participants:

M. Robinson Swift UNH - Department of Mechanical Engineering Co-Principal Investigator
Michael Gosz Illinois Institute of Technology Principal Investigator
Barbaros Celikkol UNH - Department of Mechanical Engineering Associate Investigator

Students Involved:

Ken Kestler UNH - Department of Mechanical Engineering
Michael Palzinski UNH - Department of Mechanical Engineering
Derek Michelin UNH - Department of Mechanical Engineering
Ashan Faiz Illinois Institute of Technology
Objectives: 

To provide low cost, effective and reliable offshore net-pens to commercial fishermen. To meet this objective, it is necessary to carry out finite element and reliability analysis early in the design process to optimize offshore net-pen design.

The ultimate success of the proposed research hinges on the hypotheses that the dynamic response of offshore net-pens can be adequately modeled by the finite element method, and that the design life of offshore net-pens can be predicted using experimental and numerical techniques.

Methodology: 

The dynamic response of offshore net-pens will be obtained by the finite element method. To predict the fatigue life of offshore net-pens, the Monte Carlo method will be employed.

Rationale: 

In the development of the commercial aquaculture industry, the task of designing offshore net-pens for finfish, such as cod and haddock, is very difficult due to the complex wave and current loading to which these structures are subjected. Net-pen design has developed over the years mostly by trial and error and through the construction and testing of prototypes. Because this is very expensive and time consuming, analytical or computer based models are needed to evaluate design criteria such as reliability and dynamic response before prototypes are built.

Accomplishments: 
Objective 1
To address the first objective, a finite element program was developed for predicting the dynamic response of entire offshore net pen systems. In addition, a Java-based graphical user interface was developed to make the program easy to use. Modules were developed to create fully three-dimensional rendered animations of the motion of the net pens including the surface wave motion.
The code is presently being used for research and educational purposes at the Illinois Institute of Technology. Ocean Spar Technologies is also using the code for the development and design of mooring systems, trawl nets and net pen systems. They are also using the code to help market their products and to train customers in their proper use. The code has been used extensively to assess the performance of various classes of net pen systems commonly used by the open ocean aquaculture industry.
Objective 2
To address the second objective , scale model tests were carried out in the wave tank at the University of New Hampshire. In this experimental effort, a simple test structure with a single mooring system was constructed. The structure was then subjected to surface waves of varying heights and frequencies. The motion of the cage was recorded using optical techniques. A finite element model of the test structure was then created and numerical simulations were carried out both at the University of New Hampshire and the Illinois Institute of Technology. Overall, very good agreement was obtained between the numerical and experimental results.

Publications

Available from the National Sea Grant Library (use NHU number to search) or NH Sea Grant

Thesis/Dissertation

  • Palczynski, M. (2000). Fish cage physical scale modeling. Master's Thesis, University of New Hampshire.
  • Michelin, D. (2000). Wavemaker control software for the University of New Hampshire wave/tow tank. Master's Thesis, University of New Hampshire.
  • Faiz, A. (1998). Finite element modeling and simulation of submerged flexible structures. Master's Thesis, Illinois Institute of Technology.

Proceeding

  • Swift, M., M. Palczynski, K. Kestler, D. Michelin, B. Celikkol and M. Gosz (1997). Fish cage physical modeling for software development and design applications. Nutrition and Technical Development of Aquaculture, Proceedings of the twenty-sixth U.S.-Japan Aquaculture Symposium, W.H. Howell and B.J. Keller, eds., pp. 109-206, Durham, N.H., Sept. 16-18, 1997.
  • Gosz, M., K. Kestler, M. Swift and B. Celikkol (1997). Finite element modeling of submerged aquaculture net-pen systems. Proceedings of the ASME Ocean Engineering Division International Congressional Symposium, Valentine and Jahnke, eds. OED-Vol. 14: 243-250. ASME International Congress and Exposition, Nov. 16-21, 1997, Dallas, Texas.