The deformation characteristics and flow field around knotless polyethylene netting based on fluid structure interaction (FSI) one-way coupling

Abstract

Knotless polyethylene (PE) netting is widely used in fisheries because of its excellent hydrodynamic performance and low cost. Netting deformation and the surrounding flow field distribution play an important role in determining the hydrodynamic characteristics of netting in moving water. In order to investigate the effect of solidity ratio and attack angle on drag, netting deformation, and flow field distribution through the netting, a fluid-structure interaction (FSI) model based on a one-way coupling combining the shear stress turbulent (SST) k-omega model and the large deformation nonlinear structural finite element model was evaluated. Our results showed the difference between the parallel and normal drag forces found in the present numerical model and experimental flume tank data were 9.17% and 11.58%, respectively. The mean relative error in the inclined hydrodynamic drag for different flow velocities and attack angles was 8.35%, 6.69%, and 5.37% for the nettings 1, 2, and 3, respectively. These results show that the present numerical simulation based on FSI one-way coupling can be used to examine hydrodynamic forces on netting. The flow simulation results show that there is a noticeable flow velocity decrease through the netting and a rather large velocity reduction region downstream from the netting for different attack angles. These results reveal the existence of turbulent flow due to the netting wake. It was found that the equivalent stress and total deformation increase as the flow velocity increases and solidity ratio decreases.