A Numerical Investigation for Underwater Fluid-Netting Interaction Problem

The present work investigates an application-oriented issue in the marine and fisheries researches domain. However much trawl structure codes that simulate dynamic behavior of submerged nets, in continuous interaction with surrounded ocean water, still need more accuracy and precision due to the fact that the sea water is mainly considered as a fluid with a uniform velocity and intensity, and so the effects of small turbulence rates were neglected. When this little inaccuracy occurs in the first step of the net displacement prediction, a large error could manifests in the form of the simulated net, and as consequence, drag forces wrongly estimated. In the purpose to overcome the lack of data information exchange during the fluid structure interaction, a co mputational fluid program was proposed to ensure the desired coupling. The described CFD code is based on explicit finite volume method using the method of characteristics for compressible liquid flow. The objective of this CFD package is to give a quantitative description for the entire flow filed in terms of velocity and pressure value around the knots of a submerged net structure. The discretization was performed with the finite volume method for inviscid part, and a central difference approximation for dissipation terms. A Riemann solver based on Tait equation of state and implemented into Godunov-type scheme with higher order MUSCL has been used to evaluate fluxes on control volumes interfaces. In order to verify the validity of the numerical method many tests have been carried out for multi-dimensional shock tubes, open channel fluid flow and for water flow around obstacles. The goal within this work is to achieve a coupling between the net structure and surrounding fluid through the replacement of the real net obstacle, composed of thin cylinders and spheres, by force bodies, and update the fluid package to a three dimensional model. This work will lead to a more accurate computation of the Morison force displacement of the submerged net trawl.


net deployment, Navier-Stokes, Tait EOS, Riemann solver

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Mnassri Ilyes, Le Touze David, Vincent Benoit, Alessandrini Bertrand (2011). A Numerical Investigation for Underwater Fluid-Netting Interaction Problem. Proceedings of the 10th international workshop „Methods for the Development and Evaluation of Maritime Technologies - DEMaT, pp.117-130. https://archimer.ifremer.fr/doc/00127/23834/

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