The sinking performance of the tuna purse seine gear with large-meshed panels using numerical method

Abstract

This paper reports an improved version of the numerical method used in a previous study on the dynamic simulation of purse seine gear in three dimensions. The improvement is achieved by refining the mass-spring model to take into account both the drag coefficient as a function of the attack angle and Reynolds number as applied to the setting operation of the purse seine gear. The validity of the numerical simulation is assessed by comparing the measured and calculated values for the sinking depth of the net. The numerical simulation is used to examine the sinking performance of the different designs in which large meshed-panels and netting materials are used together in the main body section of the netting. The results indicate that, compared to the prototype net, nets bearing larger mesh panels require more sinking depth with much more pronounced operational depth at corresponding times of the fishing operation when heavier netting material is used. Moreover, in the new net designs, lower tensile forces are exerted on both ends of the pure wire during pursing. The new net constructions with regard to the operational depth represent alternatives that may reduce the potential problem of frequent failed setting of the tuna purse seine gear.

The kinetic deformation of tuna purse seine: A model experiment on different shooting patterns at uniform current

“…It is attributed to the net panels in the bunt section that are made of netting with thicker twine and smaller mesh size. The purse line tension was reported 450 kN at the peak in the simulation by Hosseini et al (2011) and is larger than that in our study. This difference in purse line tension may be due to the structural difference of the nets.…”

“…Few studies reported the net geometry and dynamics monitored by underwater acoustic sensors (Misund et al, 1992;Tenningen et al, 2015). Recently, the applications of numerical simulation approach facilitate our understanding of the submerged behavior of the net (Lee et al, 2005;Kim et al, 2007;Kim and Park, 2009;Hosseini et al, 2011;Riziotis et al, 2013). These studies reported the simulated shape and movement of purse seine during shooting and pursing.…”

Identifying the Design Alternatives and Flow Interference of Tuna Purse Seine by the Numerical Modelling Approach

“…where ∀ is the volume of the mass point, and λ is additional mass coefficient. As suggested by Hossenni et al [20], the additional mass coefficient for a sphere is a constant of 0.5; for a cylinder, it is equivalent to the sine function of the angle of attack θ, and is computed as follows:…”

“…Successive research demonstrated the validity of the model with measured data from the sea trial, which evaluated the effects of netting density and sinker weight, among other factors [18]. Owing to effective monitoring and prediction of the net shape in the numerical approach, more details and arguments were put forward, for example, the transformation of the float line and purse line as the seiner drifted toward inside the net circle [19]; the substitution of a large-mesh panel with a prototype for superior performance of sinking and mechanics [20]; and the possibility of controlling the depth of the lower edge of the net by regulating the shooting speed to avoid grounding [21].…”

Numerical simulation of the knotted nylon netting panel

“…Song et al and Cao et al established the dynamic model of the tuna longline, and modelled the space shape distribution and tension distribution in different conditions [15][16] [17]. Zhang et al thought the inertial mass coefficient on knotless netting model used in tuna purse seine is the key factor for sinking performance [18].…”