Abstract: A 3-D hydrodynamic model is developed for circulating flow in a square cavity.Based upon the shallow-water equations and by using water depth to scale the vertical coordinate,the governing equations are transformed into the fixed computational domain.A high-resolution finite element scheme is incorporated to rearrange the convective terms,and a semi-implicit solution technique is employed to achieve high efficiency.The rmdel is tested against analytical solutions for the standard cases and used to study flow characteristics of the cavity circulating flow.The numerical results are in good agreement with the analytical and experimental data.The 3-D computation and analysis help to further disclose the flow patterns of the cavity flow,such as the flow behavior of unsteadiness,asymmetry,and unclosedness,the flow structure composed of circulation in both horiwntal and vertical plane,and so on.