محمد واقفی

This paper has experimentally investigated the simultaneous effect of the pier shape and position on scouring in a sharp 180-degree bend. Several experiments were performed on the bend for nine different pier shapes at three different positions and the corresponding shape factors coefficients (ratio of maximum scour depth to that of a circular pier) were evaluated for all pier shapes at each position. The presented results show that the shape factor coefficient (Ks) is mostly affected by the pier geometric shape and the effect of position of the piers is small. Furthermore, the piers with low width and sharp nose create shallow and low-volume scour hole. In contrast, deeper holes are created around the piers with wide nose and sharp edges with larger volumes. Also, the results showed that the maximum scour depth is equal to 4.22 times the pier width in the case of rectangular pier located at 90-degrees bend position and the lowest scour is equal to 2.12 times the pier width that was created around the jou.sharp pier located at the 120-degrees bend position. The maximum scour depth for the jou.sharp pier installed at the 120-degree position has decreased by 50% compared to that for the rectangular pier placed at the 90-degree position.