Flow Field Pattern and Hydrodynamic Characteristics of a Grid Device Made with Various Grid Bar Spacings at Different Inclination Angles

The grid is a crucial component in constructing grid-type bycatch reduction devices. The grid's structural characteristics and orientation significantly impact the hydrodynamic characteristics and efficacy of the separation device. Therefore, it is essential to thoroughly understand the grid device's hydrodynamic characteristics and flow field to optimize its structure. Thus, this study used CFD numerical simulation and flume tank experiments to investigate the effects of inclination grid angles and grid bar spacing on hydrodynamic forces and flow fields around a circular grid. The results indicated that the hydrodynamic forces acting on the circular grid increased with higher flow velocity and inclination grid angle, decreasing with smaller grid bar spacing. Flow velocity acceleration zones were observed at the upper and lower ends of the grid and between the grid bars. Additionally, upwelling and vortices were present at the back of the grid. It was found that an increase in the inclination grid angle accelerated the vortex and wake effects.

Automated summary

The grid plays a crucial role in constructing bycatch reduction devices, and its hydrodynamic characteristics and flow field significantly affect the effectiveness of the device. This study used numerical simulation and experimental methods to investigate the impact of inclination grid angles and grid bar spacing on hydrodynamic forces and flow fields around a circular grid. The results showed that higher flow velocity and inclination grid angles led to increased hydrodynamic forces on the circular grid, while smaller grid bar spacing reduced the forces. The study also revealed the presence of flow velocity acceleration zones, upwelling, and vortices around the grid, and the inclination grid angle accelerated the vortex and wake effects.