Modelling of Two-Phase Transient Flow with multiple Surges in Storm Water Systems by the Shock-Fitting Technique

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Current design methods for Storm Water Systems (SWS) are based on simplified representations of energy and continuity equations. This oversimplified design of the SWS has led to severe problems and costly damage to sewers (geysers, overflows, street inundations, traffic accidents and also severe electrical problems). An illustration of one of these problems happened in Montreal in 2011, where a manhole located on Wolfe Street, between the streets René-Lévesque and Sainte-Catherine, was turned into a veritable geyser on Monday July 18th, projecting sprays of storm water several meters high. Pressurized air that was blocked in the storm sewer tried to escape, taking with it large amounts of storm water. A car parked on the manhole metal cover was even violently raised repeatedly. The proposed research project will address these safety issues. An efficient set of numerical tools will be instituted for calculating hydrodynamic conditions in SWS where Best Management Practices (BMP) may be integrated. This new approach will take note of all flow types including transient flows, the presence of air, non-permanent friction, simultaneous presence of more than one wave of pressurization/depressurization, complexity of boundary conditions and water storage in manholes and BMP. The recent progress in Personal Computer advancements promote the incorporation of dynamic considerations in the transient flows modeling. New guidelines for regulations, integration of sources and End-Of-Pipe (EOP) controls into the global storm water management solutions will be recommended. The findings of this proposed project (numerical tools and SWS Guidelines) will have an important impact on the design procedure of future and current sustainable SWS. It is anticipated that significant money will be saved when using the new tools, because future SWS will be designed according to sustainable criteria and they will result in long lifespan drainage systems. Research work carried out by Professor Fuamba during the past five years related to the present proposal has contributed to the development of a few numerical tools in the urban drainage domain: (1) to assess the overflood risk in SWS, (2) to analyze the influence of manhole capacity on the propagation of the surge wave, (3) to model the SWS boundary conditions, (4) to analyze the pressurized/depressurized wave front behaviour and trapped air pockets, and (5) to simulate unsteady friction in transient two-phase flow with Godunov method. His expertise will be helpful in the creation of the new set of tools.