Mohammad Vaghefi

Totally, spur dike is an economical way to preserve morphology of rivers. Numerical methods can be useful for evaluating hydraulic parameters for spur dike because of their reduced simulation time, while experimental ones take a long time and need lots of tools to simulate any models. In this paper, flow patterns around a T-shape spur dike and a support structure, which is located upstream of the Tshape spur dike, is analyzed in 90◦ bend channel by Flow-3D model. The numerical and laboratory data are compared in longitudinal section to verify numerical model. The results show very good correspondence between numerical and laboratory data. After verification numerical model, a support structure has been installed upstream of the T-shape spur dike with 3, 5, 7 and 9 times distance longer than the length of the T-shape spur dike. The support structure altered flowpatterns and hydraulic parameters such as power of secondary flow and separation zone in all of sections. By increasing support structure distance from 3L up to 9L, the power of secondary flow around main spur dike decreases by 40–120% and the length of separation zone increases from 0.8 to 2.5 times bigger than the length of T-shape spur dike.