Mohammad Vaghefi

This article studied the effect of submergence percentage of the T-shaped spur dike on scour and flow pattern in a 908 bend. Three submergence percentages of 0, 15 and 25 were considered. The three-dimensional flow velocities were invoked using SSIIM software. The distance between maximum scour hole depth and spur dike situation was fixed by changing the submergence ratio and equalled 0.6 times the flow height at the channel inlet. It was also observed that in the range of 30%–50% of the water level, in submergence percentage of 25, the changes in the separation zone length indicated a steep slope. The range of most changes in the separation zone for other submergence percentages was 5%–25% levels. The length of the separation zone changed between 0.48 and 2.88 and the length of the reattachment zone changed between 0.9 and 4.45 times the length of the spur dike wing. The value of the dimensionless distance of the centre of the upstream vortex at the half of the spur dike height level from the spur dike situation was fixed by changing the submergence percentage and was equal to 0.45 times the spur dike wing length.