A geyser in a closed conduit system is characterized by an explosive release of a mixture of air and water through a drop shaft. Geysers are often observed in combined sewer systems (CSSs) as an explosive form of combined sewer overflows (CSOs). In the present work, the flow characteristics of sewer geyser phenomenon are studied numerically using a three-dimensional computational fluid dynamics (CFD) model for the first time. Traditionally, investigations of flow processes associated with sewer geysers are conducted through physical experiments and one or two-dimensional numerical models. However, sewer geysers are undeniably three-dimensional, hence 3D models are necessary to gain further understanding of the phenomena. The CFD model was calibrated using an experiment that exhibit characteristics of sewer geysers.
