Numerical and experimental analysis of the hydroelastic behavior of purse seine nets

The paper presents a general three dimensional hydro-elastic tool for the analysis of different types of fishing nets and aquaculture facilities. Flexible net strands are modeled by non-linear truss elements having two nodes. Hydrodynamic loads due to relative motion of the net with the surrounding fluid are computed using the Morison equation. The coupled hydrodynamic–elastodynamic equations are solved using finite element (FE) approximations. Furthermore, experimental data are presented for the drag resistance of a purse seine net, commonly used as fishing tool in the Mediterranean sea. The measurements were conducted in the towing tank of NTUA on a sample of a net. The net was tested in three configurations: vertical, horizontal and inclined at 45°. The derived drag coefficients are compared to predictions of the FEM developed model. The vertical submergence behavior of the seine in calm water is also examined, both experimentally and theoretically. Moreover, the shooting phase of the purse-seine fishing is simulated with the aim to investigate the diving behavior of the net. The flow shading effect of neighboring strands is identified as a critical parameter for the consistent predictions of the diving behavior.

► We developed a general three dimensional hydro-elastic tool for the analysis of fishing nets.
► The coupled hydrodynamic–elastodynamic equations are solved using the finite element method.
► We conducted experiments for the drag resistance of a purse seine net.
► The derived drag coefficients are compared to predictions of the FEM developed model.
► The flow shadow effect of neighboring strands is identified as a critical parameter.