Study of Vortex Settling Basin Performance for Different Discharges by Experimental and Numerical Modeling

A vortex settling basin (VSB) is an efficient continuous flushing structureto remove bed loads and coarse suspended loads. In present study, experiments were conducted in Hydraulics lab of Water Science and Engineeing Departmentat Ferdowsi University of Mashhad on a vortex settling basin model with clear water. The flow rate varied in the range of 8-22 L/s .Velocity was measured in three dimensions within the chamber using ADV. The flow field iscalculated using 3D Reynolds-averaged N–S equations, laminar case (coarse DNS) and turbulent models including standard k-ε, k-ω and Smagorinsky models. The abstraction ratio was determined, water surface counters were depicted and tangential velocity was calculated. The abstraction ratio was in range of 75-87.5%.Flow depth and tangential velocity formula were determined based on dimensional analysis and linear regression. The obtained empirical equations werecompared withother extant empirical equations. Results of turbulent models including abstraction ratio, water surface profile and tangential velocity were compared to the experimental data. Smagorinsky model showed better agreement with the experimental data and the relative error of the model was less than 3%. The free and forced vortex regions in Smagorinsky model was more similar to those in experimental data.