To enhance the effectiveness of pollution collection and self-purification within a circulating water aquaculture system, a regular octagonal aquaculture tank structure with a deflector was developed. A three-dimensional non-constant flow field numerical calculation model was established. Based on the validation of the calculation method, this study investigated the impact of geometric parameters and the positioning of flow-guide discs on hydrodynamic traits, including flow velocity distribution, vortex strength, wall shear stress, and water body mixing uniformity. The findings indicate that, while keeping the ratio of deflector diameter to pond width constant, elevating the deflector height yields a pattern of diminishing and then augmenting vortex columns at the center of the flow field. Additionally, the number of vortex rings displays a similar tendency, transitioning from decrease to increase and gradually evolving into an annular configuration from its irregular shape. Similarly, at the same height, raising the ratio of deflector diameter to pond width leads to an initial growth and subsequent reduction in the vortex column, while the count of vortex rings experiences a growth followed by a relatively stable phase. This initial growth in vortex rings is followed by a largely consistent state. By situating the deflector 20- -40 mm above the pool bottom and maintaining a pool width-to-diameter ratio of 0.05- -0.08, an amplified velocity gradient close to the pool's base can be achieved. Furthermore, this installation reduces collisions between the pool wall surface and the water body, enhancing vortex strength and promoting hydraulic mixing uniformity. This configuration fosters the necessary hydrodynamic conditions for the aggregation and expulsion of particulate matter.