Performance analysis of rectangular SIT (sediment invert trap) for stormwater drainage system

Deposition of solid particles in the stormwater sewers reduces the discharging capacity, causing inundation. A sediment invert trap (SIT) is an option that can be installed at the bottom of the stormwater sewer drain to intercept the flowing solid particles. In the present study performance of rectangular SIT were analyzed experimentally and computationally. Variation of particle trapping efficiency of rectangular SIT fitted at the bottom of the open channel flume has been studied under the interpretation of invert trap depth, flow depth, particle size, particle shape, and slot width. To predict the flow field and trap efficiency of a rectangular invert trap, 2D-VOF-DPM-CFD modelling has been carried out using ANSYS Fluent 2020 R1 software. For velocity field determination, the volume of fluid (VOF) model was used along with realizable k-є turbulence model. To predict particle trap efficiency, stochastic discrete phase model (DPM) was utilized. From experimental study and CFD modeling, it has been found that the particle trap efficiency of rectangular invert trap varied with change in the depth of invert trap, sediment size, shape factor, depth of flow and slot width. Consideration of particle shape in terms of shape factor in the modeling of solid-phase through DPM validated the CFD predicted results with those obtained experimentally with mean absolute percent error (MAPE) of 2.68%, 3.99% and 6.6% for sewer solid size ranges SS1, SS2, and SS3 respectively at all flow depths for both slot widths considered in this study.