Based on the theory of Computational Fluid Dynamics (CFD), the numerical simulation and verification method of the circular tank flow field were studied based on the large-scale computational fluid dynamics software Fluent and Particle Image Velocimetry (PIV).
A set of three-dimensional turbulent flow numerical simulation model of fish pond is established. The optimal velocity and appropriate flow field are obtained by fitting the inlet flow, inlet diameter and inlet height, and the velocity distribution and particle trajectory are analyzed; PIV technology is used to measure the flow field in the fish pond to understand the flow field and particle movement information in the fish pond.  The results show that the appropriate influent parameters could make the flow field of the circular tank more in line with the actual needs in terms of stability, sewage discharge performance and energy saving. Compared with PIV test results, the numerical simulation results are in good agreement with the flow structure of circular tank flow field, and the numerical error is basically kept within 8%, which further indicates that the numerical calculation and performance prediction in this paper can reach a certain accuracy. Finally, according to the organic combination of CFD simulation and PIV technology, a relatively complete set of fish pond flow field analysis method can be formed, which can provide research means and theoretical basis for the construction and optimization of circular tank structure in the future.