A master thesis from Aalborg University
Implementation and comparison of two numerical models for trawl cod-ends
Author(s)
Term
4. term
Education
Publication year
2018
Submitted on
2018-06-08
Pages
90 pages
Abstract
A cod-end is the rearmost part of a trawl fishing gear that collects the catch during the towing. The shape of cod-ends is of importance as it determines mesh opening and consequently influences the selectivity of fish from the cod-end. The project considers two different numerical models of the cod-end deformation: the axis-symmetric model and the 3D finite element model based on the triangular elements. The models are described and implemented in the C# code using the principles of object-oriented programming. Different solutions for improving the convergence of the Newton-Raphson method that is commonly used to find the equilibrium shape of the cod-end models are presented and compared. The numerical results from the two models are compared. A flume tank experiment is performed with a motion tracking system to sample the cod-end shape in 3D. The results suggests a good correspondence between the models for the small scale cod-ends with thin twines.
Keywords
Documents
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