Scour is a natural phenomenon caused by the erosive action of flowing stream on alluvial beds. Local scour is defined as a decrease in the bed elevation in the vicinity of an obstacle due to the dislodgement of bed sediment by the erosive action of a flowing stream. At the bridge site of a river, localized scour around abutment develop a challenging problem to the hydraulic engineers due to its significant effect on abutments stability.The occurrence and development of scour hole around bridge abutment are the main causes of bridge destruction. Prediction of the manner of formation, development and final situation of scour hole around pier is the most important in the hydraulic design of bridges. A large number of studies have been performed to estimate the scour depth around piers at simplified laboratory conditions. For accurate determination of scour depth, it is required to get a better understanding of the flow and governing mechanism around abutment. Although the flow pattern investigations were performed a lot around a pier, there are few studies around abutments. It is difficult to analyze the flow around abutments theoretically, therefore, the accurate measurements of the flow around these structures can aid to aforementioned issue.In this study the flow pattern with emphasis around the different ellipsoid shape has been studied. Experiments on the channel to length of 7 m, width 0/32 m, a height of 0/35 m and the flow rate was 13 liters per second. Channel with rectangular cross-section of the wall and the floor is made ??of traarent glass Plaksy.These tests carry out on four abutments, to form a cylinder with an ellipsoid cross section with half size of (6-2), (11-4), (15-4) and (11-6) cm and two different size og sand with size 0/75 mm and 0/26 mm is done. Obtained three-dimensional velocity measurements is at different vertical and horizontal moments Acostic Doppler Velocity (ADV) has been done.Alpha The mean velocity components, distribution of Reynolds stress, the kinetic energy of the moment with fast a sample size has been calculated. Results showed that distribution of Reynolds stress, kinetic energy within the pit water efficiency and to rely. The diameter (6-11) cm reaches its maximum. The effect of flow velocity distribution in lean secondary flow that is undeniable. Except in emphasis sometimes with a diameter of (11-6) cm in the area of flow separation is not evident. Within this role in the observed separation during lean times in the back emphasis has sometimes played.With increasing diameter abutment, depth and size, sometimes relying scour hole efficiency has increased. Width, depth and volume of the scour hole, sometimes relying o efficiency is greater than its length. Results showed that at the upstream of abutment, the velocity profiles present negative values, showing flow separation in front of the abutment. Also, a reversal flow was observed near the bed at the downstream of the abutment, revealing strong influences of the secondary currents and wake vortex in this region.
