Numerical simulation of the interaction between flow and flexible nets using a porous surface model

Résumé

Computational simulation is getting more and more attention in the recent years in the areas of understanding and improving many aspects of fisheries. Fishing nets are a major component of a fishing gear and are one of the complex parts in order to simulating them. The objective of this thesis is to use Computational Fluid Dynamics (CFD) to simulate the hydrodynamics of the fishing nets considering them as porous surfaces. This method greatly simplifies the pre-processing when the problem has complex netting geometries, as in fishing gears. The thesis also presents a new method for finding the resistance coefficients of Darcy-Forchheimer equation for porous media, required for the porous surface method and investigate the importance of both inertial and viscous porous resistance coefficients. The developed model is applied to study bottom trawling and the effect of fishing nets on sediment transport. In this study, the effect of different parameters while towing a net close to the seabed is investigated to find their significance in mobilising the sediment and on hydrodynamic forces