Fluid flow network simulation codes are commonly used as a design and analysis tool for many engineering problems such as gas distribution networks, power plants and heat pumps. Two formulations of conservation of momentum have been widely applied in fluid flow network simulation models namely those based on static pressure and those based on total pressure. The total pressure formulations are convenient in that they eliminate the difficulties associated with the calculation of the convective terms and components such as pipe junctions are treated in a straightforward manner based on total pressure losses. However, the different formulations of total pressure for compressible and incompressible flow require different formulations of the momentum conservation equation, which is inconvenient for implementation in a generic network simulation code. In this thesis a united total pressure formulation is first derived which is valid for all fluids and therefore eliminates the inconvenience of switching between the compressible and incompressible formulations. A non-iterative method for the solution of the non-isothermal discretised equations based on the total pressure formulation is then introduced and consistency is illustrated. The method appears to be very stable for subsonic flows, while rapid steady state convergence is observed. A systematic comparison is also done with traditional static pressure based methods and the similarities and differences between the two formulations are illuminated. The different time scales involved in the simulation of transient flow in fluid networks are problematic when conventional fixed time step methods are used for time-wise integration. The time scales associated with acoustic and kinematic wave phenomena as well as storage effects can differ by orders in magnitude. This thesis also presents a simple adaptive time step algorithm which can be readily used in conjunction with all the commonly used first order methods for fluid flow networks. Two test problems are selected to demonstrate the efficiency and savings obtained with this procedure. The adaptive time step algorithm correctly selects appropriate time steps for all phenomena and significant computational savings are observed for accurate integration. In addition, a procedure is implemented which automatically selects the appropriate integration method. The resulting algorithm is a fully adaptive algorithm which switches between a fully implicit method and a semi-implicit method. Two test problems are once again used to demonstrate the efficiency and savings. The fully adaptive algorithm correctly selects appropriate methods for all phenomena and significant additional computational savings are observed. / Thesis (PhD (Mechanical Engineering))--North-West University, Potchefstroom Campus, 2013

This thesis is concerned with the performance and measurement uncertainty of wire-mesh sensors in different air-water flow regimes in horizontal pipes. It also presents measurements of void fraction and interfacial velocity in such flows. It was found that the interfacial velocity measurements of the wire-mesh sensors were in good agreement with those taken with a high-speed camera and estimates of the uncertainties of these measurements are presented. Drift-flux models were fitted to the measurements and it was found that the parameters of these models were not only sensitive to the flow regime, but also to the liquid superficial velocity.

This study investigated the changes in leachate composition and clogging evolution in leachate transmission pipes and the use of methanogenesis as a leachate treatment alternative for Bioreactor landfills, by using pilot-scale and laboratory studies. The pilot-scale study consisted of a research station built at Brady Road Landfill, housing sixteen HDPE pipes of three different diameters, conveying leachate intermittently at eight different Reynolds numbers, under reasonably controlled conditions. The pipes were tested for leachate degradation, clogging evolution and hydraulic impairment over time. The laboratory studies carried out tested (1) the effect of turbulence intensity and temperature on leachate degradation and clogging effects and (2) biological pretreatment of leachate prior to injection into a bioreactor cell. The pilot study results showed that under the conditions tested, pipes developed a significant amount of organic and inorganic clog material in less than a year of operation. Since limited quantities of fresh leachate (approx. 3 m3) were used during each leachate degradation analyses, the anticipated effects of clogging in a full scale injection system are expected to be more pronounced, which can negatively impact the long-term hydraulic performance, operation, and service life of a Bioreactor Landfill. The first laboratory study showed that increasing the turbulent energy dissipation rate caused greater amounts of CO2 evolution from the leachate, and temperature increase had an impact on dissolved Ca2+ under atmospheric conditions, affecting clog development. The second and third laboratory studies showed that performing leachate methanogenesis reduces organic (COD, VFA) and inorganic (Ca2+, ISS) clog constituents within the leachate However, the rate of methanogenesis was influenced by the ratio of acetate and propionate. It is suggested that if leachate undergoes methanogenesis in a separate leachate digester prior to re-injection into a bioreactor waste cell, it may protect the pipes and other engineered landfill systems against clogging and its detrimental effects, while allowing for CH4 recovery. However, blending of leachates from different wells or cells prior to the methanogenic digester may be needed to balance the variable concentrations and ratios of acetate and propionate over time from different landfill wells and cells.

This thesis focuses on lead related drinking water quality issues in general and on hydraulic transient induced lead pipe corrosion events in water distribution systems in particular. Corrosion is a complex phenomenon, and particularly in water distribution systems, when its already challenging electro-chemical processes are influenced by numerous other physical and chemical factors. Lead pipe corrosion can itself be influenced by both the hydraulic transients and water chemistry events. To understand the relationship among hydraulic, chemical and material processes, an existing numerical 1-D transient-corrosion model for iron-pipe based systems is modified and extended to apply for systems having lead-pipes connected in series. The coupled hydraulic transient and advection-dispersion-reaction model with improved data handling facilities is applied for analyzing the transient induced lead pipe corrosion behaviors in the system for a range of options and establishes interrelationships among the parameters.

This thesis focuses on lead related drinking water quality issues in general and on hydraulic transient induced lead pipe corrosion events in water distribution systems in particular. Corrosion is a complex phenomenon, and particularly in water distribution systems, when its already challenging electro-chemical processes are influenced by numerous other physical and chemical factors. Lead pipe corrosion can itself be influenced by both the hydraulic transients and water chemistry events. To understand the relationship among hydraulic, chemical and material processes, an existing numerical 1-D transient-corrosion model for iron-pipe based systems is modified and extended to apply for systems having lead-pipes connected in series. The coupled hydraulic transient and advection-dispersion-reaction model with improved data handling facilities is applied for analyzing the transient induced lead pipe corrosion behaviors in the system for a range of options and establishes interrelationships among the parameters.

Automated construction progress tracking is becoming critical to efficient and effective construction management. More and more construction companies are putting aside the old way of tracking progress, which was mainly based on foremen daily reports and visual inspections, and are adopting 3D sensing technologies as a new and modern way of tracking progress. Technologies such as 3D laser scanners (LADARs) are investigated as a means to acquire comprehensive 3D point-cloud data which can then be studied by management to determine the progress of construction. Although being much more accurate and efficient than visual inspections, this new progress tracking approach can be improved by applying object recognition algorithms that enable an automated progress tracking. This new approach has been investigated by other researchers, but only for progress tracking of structural elements. This study focuses on mechanical objects such as pipes and ducts, which would give the progress tracking a better level of detail and a wider scope. The investigation is carried out on a field database acquired during the construction of the Engineering VI Building at the University of Waterloo. It was found that the laser scanning technology is a suitable method for acquiring point-clouds of pipes and ductwork, and also that the object recognition algorithm used in this study allows a progress tracking as well as a quality tracking of the HVAC system installation.

Thesis (M.S.)--University of Hawaii at Manoa, 2006. / Includes bibliographical references. / vii, 49 leaves, bound ill. 29 cm

Thesis (M.S.)--Ohio University, November, 2001. / Title from PDF t.p.

Thesis (M.S.)--Ohio University, June, 1999. / Title from PDF t.p.

Thesis (M.S.)--Ohio University, June, 2004. / Title from PDF t.p. Includes bibliographical references (leaves 78-80).