Near Bed Turbulent Bursting Process Analysis around a Spur Dike in a Channel Bend

In this paper the near bed turbulence bursting process around a spur dike is investigated. For this purpose the flow field around the spur dike was measured using ADV apparatus and the analysis of the turbulence bursting process was done by using the data. Different parameters such as mean velocities, probability of each events and angle of sweep and ejection event, stability of events, Reynolds shear stress and turbulent energy flux were used to analyze the events. Results of this paper confirm that there is strong relation between scour process and near bed flow field. The latter parameters can be used to find the region with scour potential. The upstream and downstream reverse flows make strong interaction events but the sweep and ejection events are dominant in the outer region of the reverse flow and in shear flow region and they have the maximum strength. Comparison between the sediment transport process around the spur dike with low and high submergence showed that near the upstream nose of the low submergence spur dike, the Reynolds shear stress is one of the sediment transport doer. However, in high submergence spur dike the maximum value of bed shear stress occurs in the downstream region of the spur dike where the overflow plunges to the bed surface. The differences between the maximum bed shear stress of the low and high degree of submergence of spur dike is one of the reasons for larger scour hole around the low submergence conditions as compared to the high submergence condition. In addition, larger values of the turbulent kinetic energy flux in low submergence condition is another reason.