Mohammad Vaghefi

In this work, the three-dimensional flow around piers in river meanders under rigid bed conditions was modeled. The software ANSYS FLUENT was used to perform the simulation. The study was carried out in a 180° curve accompanied by cylindrical piers with a diameter of 5 cm and a slope angle of 21° under rigid bed conditions. The results of the comparisons showed that this model can help simulate the flow pattern around inclined bridge piers in bended channels with acceptable accuracy. To analyze the flow pattern, the work was followed by studying the effect of the parameters that affect the physics of the problem: the relative radius of curvature of the curve, the location of the piers within the 180° curve, and the arrangement of the piers relative to the flow direction. The results showed that increasing the relative radius of curvature as well as the range of the bend reduced the tangential velocity values; the minimum tangential velocity value occurred at a relative radius of curvature of 5. With the pier group installed in the direction of flow, the maximum secondary flow power occurred at the 60° position at about 18.8%, while with the pier group installed across the flow, the maximum secondary flow power occurred at the 120° position at 14.2%. A comparison of the vorticity at the perpendicular and downstream positions showed that the vorticity values at the 60° and 120° positions were greater than the corresponding values at the 90° position in both cases.