Predicting Manhole Mixing Using a Compartmental Model

Manholes in combined sewers may become surcharged during storm events, resulting complex mixing conditions. Although manhole hydrodynamics are reasonably well understood, predicting across a remains challenge. An analytical compartmental model for manholes, based on jet theory, has been further developed and applied to generate cumulative residence time distributions (CRTDs), which describe mixing. The modeled CRTDs were compared with the experimentally derived of over 850 configurations evaluate how new represents physical processes. underpredicts short-circuiting manholes diameter pipe ratios greater than 4.4 consequently overestimates Otherwise, show good agreement experimental CRTDs. key that not represented current software modeling packages, assume instantaneously well-mixed. provides predictions downstream concentration profiles, although reduced peak concentrations those where is well-predicted. Despite this, still predicts closer recorded data complete well-mixed assumption. As an requiring no inputs other geometry, applies wide range configurations, robust, useful practical applications.