Using a multiphase flow numerical model to simulate geysers in stormwater systems

The temporary belowground storage of stormwater is useful in urban areas to prevent flooding. During intense rain events the conduits can fill rapidly and completely undergo a transition from open channel flow to pressurized flow. This transition can create large discrete pockets of trapped air as the interface advances into the free-surface portions of the system. These pockets pressurize in the horizontal reaches of the system and then are released through vertical vents, potentially creating a geyser condition. There have been some experimental and numerical investigations of the geyser effect, but the complex nature of the physics and geometry make this a challenging problem. Numerical studies have treated the geyser as a lumped mass or rigid column, with no consideration to the multiphase flow dynamics. This work presents a preliminary finding of a multiphase flow numerical model to capture both the liquid and gas dynamics, as well as the necessary interaction to create the geyser.