Computer simulation and flume tank testing of scale engineering models: How well do these techniques predict full-scale at-sea performance of bottom trawls?

Abstract

a b s t r a c tA Canadian demersal survey trawl (Campelen 1800) was used to investigate the differences in trawl geometry and resistance using dynamic simulation, flume tank testing, and full-scale at-sea observations. A dynamic simulation of the trawl was evaluated using DynamiT software. A 1:10 scale model was built and tested in a flume tank at the Fisheries and Marine Institute of Memorial University of Newfoundland (Canada). Full-scale observations of the Campelen 1800 in action were collected during the 2011 fall multi-species survey aboard the research vessel CCGS Teleost. The numerical and physical modelling data were assessed to determine their ability to predict full-scale at sea performance of the Campelen 1800 trawl. The numerical simulation data were also compared against scale model engineering performance under identical conditions. The study demonstrates that the ideal method with which to accurately predict full-scale at-sea performance of bottom trawls or used for designing a trawling system probably does not exist. Therefore, the importance of using two or three complementary tools should be encouraged as an ideal process for designing a trawling system and/or assisting the gear development circle.

Flume Tank Evaluation on the Effect of Liners on the Physical Performance of the Antarctic Krill Trawl

“…Lower bridle tensions for all trawl models can be achieved at lower towing speed and door spread, and higher heavy bob weight and the ratio of buoyancy to F/G, following similar trends obtained by Feng et al (2012Feng et al ( , 2017, Nguyen et al (2015), and Li et al (2017). These findings are very interesting for the Antarctic krill fisheries and have resulted in a recommendation to towing krill trawls at lower towing speed from 2.0 to 2.5 knot, as Antarctic krill have weak swimming ability (Juáres et al, 2018).…”

“…The length of the liner directly relates to the escape of krill through the meshes of the trawl, thus affecting size selectivity and catch retention. This study demonstrates that model tests in the flume tank can be used to predict the full-scale engineering performance of Antarctic krill trawl at the sea, despite the fact that under real fishing conditions, the performance of trawl would likely have greater uncertainties due to variations in oceanographic conditions (Nguyen et al, 2015;Thierry et al, 2021b).…”

Industrial double rig trawl fisheries in the southeastern and southern Brazil: characterization of the fleet, nets and trawl simulation

“…All of this confirms that the dynamic simulation of trawl nets is becoming a more important option for the study of trawl nets, and it must be complemented with other sources of information, either through direct measurements or the use of scale models (Queirolo et al, 2009;Nguyen et al, 2015).…”

“…In some cases, portable equipment can be used to carry out a net characterization, but this requires a specific sampling design during some fishing days. In order to advance on the knowledge of the hydrodynamic performance of trawl nets, it is known that the use of dynamic simulation tools provides a valid approach with an acceptable level of error during design and evaluation stages (Vincent, 1999;Queirolo et al, 2009;Nguyen et al, 2015). Essentially, the most advanced knowledge stages require the use of supplementary hydrodynamic performance tools, such as the use of flume tanks and direct measurements in the sea according to the specific objectives (Winger et al, 2006).…”

Comparative fishing to evaluate the viability of an aligned footgear designed to reduce seabed contact in northern shrimp bottom trawl fisheries

“…While the predictive reliability of scaled engineering models in flume tanks can be quite good (Nguyen et al 2015a), the authors recognize that no actual field monitoring was conducted in situ to document the contact area of the control or experimental trawls with the seabed. It is conceivable, for example, that the increase in observed door spread (+4%) and wing spread (+5%) in the experimental trawl may have affected the alignment of the discs in the wing sections of the trawl, although in the authors' opinion this would have had negligible effect on the degree of seabed contact.…”