42 DECEMBER 2014 • WORLD AQUACULTURE • WWW.WAS.ORG help optimize aquaculture netting used in future applications. Extrapolating our small-scale results to a 20-m diameter net pen in open-ocean conditions, a 10-mm increase of the mesh void can lead to a 0.4 GN reduction in the drag force. Conclusions With net-pen farms increasingly situated farther offshore, it has become even more important to understand flow dynamics around aquaculture pens to predict the load forces applied to the net and to optimise the farm environment. We have observed that a change in surface porosity can result in drastically different flow dynamics and changed dispersion rates of particulate matter through nets.1 A change in surface porosity has an impact on the drag force, as expected. However, porosity alone is not the main factor in determining the level of drag, but that it is primarily imposed by the mesh void size and to some lesser extent by twine thickness. These results provide a better understanding of the fluidstructure interaction on a porous structure similar to those used in commercial net-pen aquaculture and provide a starting point for netpen design optimization. Acknowledgments The experiments spanned a one-year period and are part of an ongoing research project on nets of aquaculture pens. This work is supported by a Faculty of Engineering Faculty Research Development Fund at the University of Auckland, New Zealand. Notes B. Levy, J.E. Cater, R.J. Clarke and J.P. Denier, Department of Engineering Science, University of Auckland, New Zealand H. Friedrich, Department of Civil and Environmental Engineering, University of Auckland, New Zealand Corresponding author e-mail: j.denier@auckland.ac.nz 1 Levy, B., H. Friedrich, J.E. Cater, R.J. Clarke and J.P. Denier. 2014. Impact of twine/mesh ratio on the flow dynamics through a porous cylinder. Experiments in Fluids (submitted). References Klebert, P., P. Lader, L.C. Gansel and F. Oppedal. 2013. Hydrodynamic interactions on net panel and aquaculture fish cages: A review. Ocean Engineering 58:260-274. Meggitt, D. and T. Gulli. 2014. An autonomous wave-powered energy system for net-pen aquaculture. World Aquaculture 45:39-41. Williamson, C.H.K. 1996. Vortex dynamics in the cylinder wake. Annual Review of Fluid Mechanics 28:477-539. Wood, C.J. 1967. Visualization of an incompressible wake with base bleed. Journal of Fluid Mechanics 29:259-272. 30 YEARS Aquaculture CanadaOM 2014 June 1-4, 2014 St. Andrews, New Brunswick “AAC 30th Anniversary – Excellence in Research & Innovation” This is an exciting year for the Aquaculture Association of Canada as it marks our 30th Anniversary! There have been numerous innovations in the aquaculture industry over the past 30 years and we want to celebrate the contributions that the Association and its members have had on the successful development of the industry in Canada. The annual conference serves as the main event for the Association and is Canada’s national forum to bring together the business, science and technology of aquaculture. Conference coordinator: Joanne Burry Tel : 709-437-7203 Email : jmburry@nl.rogers.com www.aquacultureassociation.ca Of Excellence in Research & Innovation
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