numerical simulation of skewed slot effect on local scour reduction

local scouring around bridge piers is a natural phenomenon caused by the erosive process of flowing stream on alluvial beds. the 3d flow field around bridge piers interacting with the bed materials increases complexity of local scour process. the local scour depth develops in accelerated flows and if it is not predicted correctly, the bottom level of local scour hole will exceed the original level of pier foundation. in this case the failure of bridge will occur. using different methods of local scour countermeasure for reducing the magnitude of local scouring depth and retrofitting costs would be economically efficient. as a local scour countermeasure method, applying slots in the piers could reduce the local scour depth around circular piers. since in natural streams the piers are skewed to flow in most cases, it is more feasible to evaluate the skew slots effects on scour reduction. the present study focuses on numerical simulation of maximum depth of scour due to the installing of slots in various angles of flow attacks by employing a 3d numerical model (ssiim program). the results show the ability of ssiim for modeling the local scouring around bridge piers with slots.