Dynamics of cyclic and violent geyser eruptions in storm sewer systems: an experimental and numerical approach

TL;DR: This study analyzes sewer geyser eruptions through experiments and numerical models, introducing non-dimensional parameters to generalize geyser behavior. Results show cyclic eruptions occur with continuous air supply, while non-continuous air supply generates more forceful eruptions.

Abstract: This study aims to analyse the cyclic and violent nature of sewer geyser eruptions through experimental and numerical approaches. The contribution of this research lies in introducing non-dimensional parameters to generalize geyser behaviour across different system scales. An experimental setup was developed to simulate geyser events under controlled conditions, enabling precise observation of pressure variations and flow behaviour. The setup consists of a closed flow loop incorporating PVC pipes, a dropshaft, and a water piping system to maintain constant pressure boundaries. Results show that continuous air supply produces lower, cyclic eruptions when pressure head gradients exceed specific thresholds ( $ S_{AD} < 0.6\% $ SAD<0.6%, $ S_{AI} < 1.6\% $ SAI<1.6%). In contrast, non-continuous air supply generates more forceful and non-cyclic eruptions due to the build-up of isolated air pockets that release explosively. These eruptions require higher gradient values ( $ S_{AD} > 5\% $ SAD>5%, $ S_{AI} > 3\% $ SAI>3%), indicating the role of boundary conditions and air supply methods in controlling eruption intensity and periodicity.