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Title: Modelling of wave generation in sewer systems by intermittent discharge devices using the Saint-Venant and Boussinesq equations
Author: Alves, Wolney
ISNI:       0000 0001 3419 047X
Awarding Body: Heriot-Watt University
Current Institution: Heriot-Watt University
Date of Award: 1996
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Although the International Drinking Water Supply and Sanitation Decade (1981-1990) has brought important acquirements in terms of covered population increasing and in terms of conceptual and technical development, the present deficit points to the necessity to continue and improve the Decade achievements. Innovative, appropriate and low-cost technologies played a major role on this struggle. Unsteady flow equations applied to sewer networks are a precious instrument on the description of actual phenomena on sewers leading to more rational and economic design, construction and operation. The use of intermittent discharge devices as a means of reducing pipe slopes in separated sewer networks, leading to a reduction in construction costs, mainly in flat areas, is explored. A unidimensional model directed to simulate the flow generated on sewers through intermittent discharge devices is presented. Two mathematical equations are used to the generated wave modelling: the Saint-Venant and the Boussinesq equations. Numerical integration, through finite-difference methods, is used to solve mathematical systems. Three numerical models are applied: the method of characteristics, McCormack scheme and the two-four scheme. A computer program was developed providing hydraulic variables simulation. Three alternatives are embraced: the Saint-Venant equations using the method of characteristics and the McCormack scheme and the Boussinesq equations using the "2-4" scheme. Linear and Everett and Newton—Gregory interpolation are provided on the method of characteristics. Lister (1960) and Standing (1986) iterative process are also provided. An analysis method to determine the flow regime on the method of characteristics is incorporated in the program. Special schemes for friction and vertical acceleration adjustment are also available. Comparison with laboratory data showed that in general the "2-4" scheme produced better results in terms of wave velocity. The wave generated through the developed experimental discharge device had better simulated results in terms of water depth profiles and wave velocity using the Boussinesq equations, solved through the "2-4" method. The model showed clear response differences depending on friction and vertical acceleration values. Strictly under Boussinesq's hypothesis however, vertical acceleration has shown not to be relevant. The oscillation of the wave peak water depth along the pipeline was an interesting finding of laboratory works. A major problem on the processing was the formation of a pulse on the wave front. Research continuation and field application are planned.
Supervisor: Swaffield, John Sponsor: The British Council ; Fapesp - Fundação de Amparo à Pesquisa do Estado de São Paulo (Brazil) ; CNPq - Conselho Nacional de Desenvolvimento Científico e Tecnológico (Brazil)
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: Sewers ; hydrodynamic modelling ; computacional fluid dynamics