Some of the major concerns regarding the sewer overflow include serious environmental, aesthetic and public health problems in receiving water bodies. Due to increasing public complains engineers are focusing on retention of the entrained sewer solids within the sewer overflow device. Present study investigates the hydrodynamic characteristics of a self cleansing sewer overflow device with no mechanical or electrical components. The device has a rectangular tank and a slotted ogee weir to capture the gross pollutants. The proposed device is deviated from traditional weir as in a traditional weir flow along a creek; the incoming flow is stable without any significant reflection. Whereas, significant reflections of inflow will occur due to smaller dimension of the device, which needs to be accommodated within existing urban sewerage system.

State of art Computational Fluid Dynamics (CFD) technique was used to simulate the flow phenomena and compared with analytical results. In both cases atmospheric pressure was consider as a boundary condition over the ogee weir, therefore good agreement between analytical and numerical results were found. Results show curved face of the ogee spillway remains in contact with the weir at all low flows. Near the right side of the device, where inflow is reflected by the side wall, velocity and water level were found almost twice compared to normal flowing water on the sloping plane. Flow undulations across the weir will hamper effectiveness of self-cleansing, as shear force from uniformly distributed (across the width) flow will effectively remove the trapped pollutants from the screen.