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Chun-Woo LEE Division of Marine Prodution System Management Pukyong National University, Busan, KOREA

Trawl gear design to improve the energy efficiency using computer aided method. Chun-Woo LEE Division of Marine Prodution System Management Pukyong National University, Busan, KOREA. Issues related energy use in Fisheries. Increased focus related to the environmental impacts

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Chun-Woo LEE Division of Marine Prodution System Management Pukyong National University, Busan, KOREA

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  1. Trawl gear design to improve the energy efficiency using computer aided method Chun-Woo LEE Division of Marine Prodution System Management Pukyong National University, Busan, KOREA

  2. Issues related energy use in Fisheries • Increased focus related to the environmental impacts • Achieve sustainable management of natural resources • Main aim of Kyoto protocol • Responsible Fishing (Cancun, Mexico in 1992) • Financial difficulties in fishing industries

  3. Factors affect the energy consumed • Distance to the fishing ground • Searching for fish school • Operation of the fishing gear, Preservation of the catch • Current researches related to reducing the CO2 emission from fisheries Fishing vessel Operation Design of fishing gears

  4. Numerical Method Numerical approach • is an economical way to predict the results. • provides the alternative plans to approach to the reality. • includes the uncertainty in the results. Process • Establishing the numerical model • Computing the model • Analysis of hydrodynamic forces on the gear • Improve design by changing structure or materials

  5. Numerical Modeling • Physical features of the structures • Consists of various materials • Exposed to various loads • Deforms to a considerable degree in the current and waves • Non-linearity • Difficulty to describe the mathematical model due to the environmental factors • Derive the non-linear and stiff equation

  6. Mass spring model Modeling of fishing gear

  7. Modeling of Netting Mesh grouping • Placement of virtual mathematical mesh using mesh grouping method and vector notation of the element.

  8. Equation of motion Internal Force External Force Added mass & Added mass coefficient

  9. Hydrodynamic force Resultant Velocity Vector Drag and Lift Force Unit Vector for Lift Force Volume of Net Buoyancy and Sinking

  10. Drag coefficient in connection with ReD & Attack angle

  11. Lift coefficient in connection with Attack angle

  12. Numerical methods – Newmark- β Governing equation of motion and Numerical methods • The position • The velocity • The acceleration • The relative error

  13. Flow chart of the design and simulation using a computer

  14. Trawl design plan and simulation

  15. Database for designing fishing gears

  16. Trawl design plan and simulation • Mid-water Trawl net in front view • Mid-water Trawl net in 3D view

  17. Trawl design plan and simulation • Pair Trawl net in 3D view • Multi Trawl net in 3D view

  18. Purse seine design and simulation tool

  19. Simulation of a purse seine Shooting process of purse seine net Pursing process of purse seine net

  20. Design of the gear using a computer

  21. Analysis of the resistance on the gear Tension (kgf) Simulation condition Section 1 372.92 • Towing speed: 4 [kn] • Net part divided into 4 parts for analyzing the resistance • Changing the thickness: 2/3, 1/3 times with Dyneema Section 2 1496.14 Section 3 436.91 Section 4 5474.54 7735.51 Total

  22. Comparison 1 Distance between Otterboards [m] Area of net mouth [m2] • Changed section : section 4 Tension[kgf] Height[m] Top view Side view 28.88 104.51 666.86 7735.51 2/3 times 1832.07 128.20 5565.39 42.38 Applied Dyneema in section 4 with reducing a thickness 1/3 times 2531.81 137.54 5009.83 53.09

  23. Comparison 2 Distance between Otterboards [m] Area of net mouth [m2] • Changed all sections Tension[kgf] Height[m] Top view Side view 104.51 28.88 666.86 7735.51 2/3 times 119.48 1448.30 6206.47 36.07 Applied Dyneema in all sections with reducing a thickness 1/3 times 3069.71 143.13 4639.89 63.71

  24. Construction costs • Calculated netting materials excluded rigging parts • Rigging parts will be necessary to adjust for appropriated shape of a gear Construction costs 11 6 2.7 1 2 Applied Dyneema with reducing a thickness

  25. : Resistance of a gear E.H.P : Effective horse power : Resistance of a vessel : Relative current speed pass through a vessel Fuel consumption & reduction Fuel reduction ratio with changing the thickness of ropes compared to present type of the gear

  26. Numerical Method Discussion • can calculate the drag force on fishing gear under various conditions • can determine the material costs to build fishing gear • can make it possible to design an optimum fishing gear by balancing increased costs and reduced drag forces • will help design low-carbon emission fishing gear by saving both time and cost

  27. Thank you for your attention !!

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