Studying the arrangement of submerged vanes group in a straight alluvial channel using numerical modeling of flow and bed topography around a single vane

Abstract

Submerged vanes are installed in waterways bed. These structures are usually used in groups and their main performance is to create an eddy current which leads to change in stream flow pattern and the bed topography in waterways. Performance of submerged vanes group depends on their arrangement and size. In this study using SSIIM numerical model, hydrodynamic analysis of flow pattern and bed topography around a single submerged vane in a straight channel was done and tried to estimate proper arrangement of submerged vanes group. The geometry of arrangement consisted of longitudinal distance between consecutive vanes, transverse distance of two adjacent vanes, and transverse distance of submerged vanes from the outer wall. Therefore, after verification of the results of numerical model with experimental data, flow pattern and topography of the bed around a vane with different dimensions and angles (in suggested domain) were investigated and analyzed. In this order, values of transverse and longitudinal distances of scouring hole at high-pressure and low-pressure sides of the vane from center of the vane were measured. Also values of transverse and longitudinal locations of the maximum scouring hole and maximum sedimentation downstream of the vane were determined. The results of these parameters were used to estimate the location of adjacent vanes. To reduce number of modes, the Taguchi method is used in design of simulations. Finally, mathematical relations are derived for geometry of arrangement versus vanes dimensions and angles. Comparison of the results of this research with the results of previous researchers, who have studied submerged vanes groups, showed that accuracy of the method used in this study is acceptable. The numerical results showed that the values obtained for the transverse and longitudinal distances of vanes are almost in the same range of previous laboratory studies.