Flow state around hydraulic structures such as groin and weir composed of connected stones is very complicated. Therefore, more accurate approaching velocities must be used in designing these structures considering the structure's stability against flood attack. In this paper, three-dimensional flow simulation for hydraulic structure composed of connected stones was carried out to get more proper approaching velocity and its applicability was investigated. Numerical results can explain fairly well the water level and velocity profiles around permeable hydraulic structure composed of connected stones. Furthermore, the obtained approaching velocity is considered accurate enough for design use.
