Evaluating Storm Water Management Model Accuracy in Conditions of Mixed Flows

Abstract

Stormwater systems, while designed to operate in free surface flow conditions, can undergo transition to pressurized flows during rapid filling conditions where inflows exceed the conveyance capacity of sewers and tunnels. Such conditions are referred to as mixed flows or flow regime transitions and pose a challenge to traditional unsteady numerical models. The Storm Water Management Model (SWMM) has an unsteady hydraulic solution algorithm based on an EXTRAN module that can simulate mixed flows.