In this research, the hydrodynamic effects of the flow around a submerged rectangular surface near the bed and the free surface of water has been investigated. This analysis was done using FLUENT and the multiphase method of volume of fluid (VOF) and the standard k-ɛ model was used to simulate turbulence. After checking the mesh and computational space independency, first the effects of changing the depth of the geometry immersed in water from the free surface and also changing the velocity of the fluid flow on the waveform of the free surface and hydrodynamic coefficients were investigated and then the effects of close This geometry has been evaluated on the floor. The results of the present research show that as the submerged rectangular plate moves away from the free surface (increasing the depth) at a specific water velocity, the drag coefficient and negative effect increase, and on the contrary, with the increase of the fluid velocity at a specific depth from the surface, the performance The hydrodynamics of the system increases. Also, as the geometry approaches the water bed (floor), the hydrodynamic performance is improved, while there is no significant change in the drag coefficient. In addition, at a certain depth from the floor, the hydrodynamic performance increases significantly with the increase in fluid velocity.