Hydraulics & Waterways

Oral

394700 - Simulating Geyser Events in the City of Minneapolis Tunnel System Using CFD and Designing Mitigating Measures

Monday, June 4
10:30 AM - 12:00 PM
Location: Regency Room

Geysers in stormwater tunnel systems are public safety hazard and have been observed in many cities such as Edmonton, Chicago, Manitou Springs, Minneapolis, Montreal and Pittsburgh. Over the past few decades, there have been efforts to predict geyser events and to design mitigation measures to prevent or control geysers. Current research indicates that the geysers are caused by a violent release of air-water mixture as a result of trapped air pockets in tunnel systems. Geyser events have been simulated via experimental and numerical models in the past. However, up to now, the simulations have been either too theoretical or conducted for simplified geometries and/or scenarios, with little or no practical use for control or prevention.
Herein, two-phase flow computational fluid dynamics (CFD) models have been developed to simulate observed geyser events and to evaluate design alternatives for geyser mitigation measures on a tunnel segment in the City of Minneapolis, MN. The CFD models were validated using observed data such as pressure, geyser height and manhole maintenance records. The observed data was complemented with results from precursor hydrology models (i.e. velocities and pressure values for different locations in the tunnel). The model results allowed us to have an informed decision on geyser mitigation alternatives based on parameters such as geyser height, force on the manhole cover and volume of water expelled per geyser. Finally, three design alternatives were evaluated which intended either to contain the water expelled by the geyser (a surge chamber and an oversized manhole) or to avoid the violent release of air-water mixture (a modified tunnel connection).

Christian Frias, PhD., PE.

Water Resources Engineer
Barr Engineering Co

Christian Frias has over seven years of consultant experience. His areas of expertise include surface-water and river-morphodynamics modeling, computational fluid dynamics (CFD), software implementation, high-performance computing, computer programming, hydraulic structure design, and GPS surveying at open-pit mining sites. He also has experience collecting field data on large rivers in the United States, Brazil, and Peru. Christian’s work at Barr includes CFD modeling, dam failure modeling, river migration modeling, toe and bank scour calculations, and hydraulic analysis. He has published four articles in peer-review journals on river morphodynamics and large eddy simulations.

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Brandon Barnes, PE.

Barr Engineering Co

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Omid Mohseni, PhD., PE.

Senior Water Resources Engineer
Barr Engineering Company

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