Supercritical flow in bend manholes

Sewers direct wastewater to the WWTP. Outflow might occur at bend manholes if the flow is supercritical. So far, the hydraulic design bases for such bends are limited to a few geometries requiring large dimensions. These can hardly be prefabricated and transported. This raises the question of the performance of alternative bend geometries, which are systematically tested using calibrated hydrodynamic simulations. A generally applicable design approach of the hydraulic capacity of such variable bend manhole geometries results.