Investigation of local scour around tandem piers for different skew-angles

In the present study the effect of the skew-angle of the alignment of tandem piers on local scour depth around them is investigated. The tandem piers were aligned with different skew-angles of theta = 0 degrees, 30 degrees, 45 degrees, 60 degrees, 90 degrees with respect to the flow direction. The results indicate that with the increment of the skew-angle, the influence of sheltering effects is decreased. In other word, since the sheltering effect of the upstream pier is declined (which reduces the approach velocity for the downstream pier) the scour depth around downstream pier increases. The results show that the maximum scour depth occurs at both piers for the skew-angle of theta = 45 degrees. Furthermore, the best configuration to aligned tandem piers was achieved at the skew-angle of theta = 30 degrees.