Effect of submerged vanes on the scour occurring at a cylindrical pier

Abstract

The principal purpose of this research was to study the effect of a submerged vane as a countermeasure technique on local scour at a cylindrical pier. For this purpose, several heights of vane, angles of orientation, and flow depths were evaluated, all for a constant Froude number. It was found that for an isolated vane, a greater depth of scour was experienced at higher flow rates and/or at greater flow depths with all vane combinations and orientations. It was also found that not all types of single isolated submerged vanes can be used as a scour countermeasure at cylindrical piers. The highest reduction in scour was achieved for an angle of 8.5° and a flow depth of 20 cm for a vane height equal to 0 cm while the most exacerbated case occurred with a vane angle of 18.5° and a flow depth of 10 cm for a vane height equal to 5.7 cm. So, it was concluded that for vane heights other than the 0 cm investigated in this study, an increasing scour depth is experienced at cylindrical piers compared to control. For two vanes attached to the pier, a reduction of 87.7% in scour depth next to the pier was achieved for a constant flow depth (i.e., 15 cm), a constant vane angle (i.e., 18.5), and at 0 distance upstream from the pier for a vane height of 0 cm