Geyser Episodes Created by the Release of a Sequence of Discrete Air Pockets in Vertical Shafts

Stormwater geysers are an undesired operational issue that occurs when runoff in stormwater systems returns to the grade through vertical shafts when these systems are undergoing rapid filling. Among other mechanisms, the release of large entrapped air pockets through ventilation shafts is a likely cause of many recently reported geyser events. The existing investigations upon air pocket release induced stormwater geyser indicate that the water level displacement and velocity in the shafts, representing the geyser intensity, is related to the size of released air pocket, size of the ventilation shaft, and the initial standing water depth in the shaft. However, there has been fewer studies considering the release of various discrete air pockets through vertical shafts. Considering that various reported geysers are linked to a sequence of air-water releases, it is possible that these are linked to the release of various air pockets through shafts. The present research implements a series of computational fluid dynamics (CFD) simulations on the stormwater geyser episodes with the release of varying number and size of air pockets. It is expected to qualitatively understanding the process of multiple air pocket release and quantitatively investigate the flow characteristics of the geyser with a sequence of breakthroughs.