NDLI: Experimental Investigation and Numerical Modeling of Hydrodynamic Force Characteristics and Deformation of an Elastic Net

Content Provider	The American Society of Mechanical Engineers (ASME) Digital Collection
Author	Ito, Sho Kinoshita, Takeshi Kitazawa, Daisuke Bao, Weiguang Itakura, Hiroshi
Copyright Year	2011
Abstract	With the increasing worldwide demand of seafood and environmental problems in coastal aquaculture, offshore area has been increasingly expected to be utilized for aquaculture. An offshore aquaculture system has fewer effects on the surrounding marine environment through the rapid diffusion of organic wastes from the cultured fish than a coastal one. The offshore area then provides clean waters for cultured fish. On the other hand, the offshore aquaculture system is subject to the severe natural condition such as typhoon attack. Actually, in the current aquaculture system, the offshore sea cages are always submerged around 10m below the sea surface to avoid the effects of high waves and strong currents. However, the safety of the sea cage against the incident wave has seldom been examined, while that against the water current has been analyzed by model tests in tank and numerical simulation. We investigated the hydrodynamic force properties of a heaving sea cage in the previous work and its results proved that the deformation of net much affects on sea cage’s motion characteristics. To study the most fundamental problem, we investigated the hydrodynamic force characteristics of a rigid net as a first step and explained that these relate to its porosity and wave conditions. As a second step, in the present study, we investigate hydrodynamic force properties of an elastic net. Six square-shaped textile net models which are made of elastic strings and metallic frame are arranged. Three different porosities (0.53, 0.64 and 0.74) and two different net’s tension (10 and 50 N/m) on each porosity are employed; that is, we arranged 6 elastic net models. Forced heaving tests and diffraction tests are carried out. In addition to measuring heave force, the deformation of net surface is measured by a video image analysis system. To compare with the experimental results, we calculate hydrodynamic forces and the deformation of net using a boundary element method. The boundary condition on elastic net is that the normal velocity to the surface is not zero but proportional to the pressure difference. The deformation is also taken into consideration.
Sponsorship	Ocean, Offshore and Arctic Engineering Division
Starting Page	23
Ending Page	33
Page Count	11
File Format	PDF
ISBN	9780791844373
DOI	10.1115/OMAE2011-49213
Volume Number	Volume 5: Ocean Space Utilization; Ocean Renewable Energy
Conference Proceedings	ASME 2011 30th International Conference on Ocean, Offshore and Arctic Engineering
Language	English
Publisher Date	2011-06-19
Publisher Place	Rotterdam, The Netherlands
Access Restriction	Subscribed
Subject Keyword	Water Deformation Seas Computer simulation Boundary element methods Fluid-dynamic forces Organic wastes String Waves Diffusion (physics) Pressure Textiles Water currents Shorelines Diffraction Ocean engineering Boundary-value problems Tension Porosity Safety Currents
Content Type	Text
Resource Type	Article

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