Papers by Roger A Falconer - Cardiff University
Journal of Geophysical Research, 2011
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Environmental Modelling & Software, 2011
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Details are given herein of the refinement and application of a two-dimensional depth integrated ... more Details are given herein of the refinement and application of a two-dimensional depth integrated numerical model to predict geo-morphological changes in tidal basins. An Alternating Direction Implicit finite difference algorithm has been used for solving the governing differential equations, which consist of the conservation of mass and momentum for the hydrodynamics, the transport equation for suspended sediment fluxes and the sediment mass conservation equation for bed level changes. The model includes several criteria for the initiation of motion (i.e. Shields (1936), Kolahdoozan (1999) and Zanke (2003)). As the flow is highly turbulent, and its components have a random nature, many researchers have tried to express the sediment transport processes by using stochastic approaches. In the current study, both deterministic and stochastic methods were included in the numerical model to show their accuracy and efficiency. To evaluate the numerical model results laboratory measurements...
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Water, 2015
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Water, 2015
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Natural Hazards, 2015
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Journal of Hydro-environment Research, 2015
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Journal of Hydro-environment Research, 2015
ABSTRACT The hydrodynamics and mixing processes in small- and full-scale baffled disinfection tan... more ABSTRACT The hydrodynamics and mixing processes in small- and full-scale baffled disinfection tanks are studied experimentally and numerically. Velocity and tracer transport measurements are carried out to quantify the hydrodynamics and to obtain reliable data used to validate a three-dimensional computational fluid dynamics (CFD) model. The flow in the tank under investigation is extensively three-dimensional due to the existing inlet condition of the tank, resulting in short-circuiting and internal recirculation, particularly in the first three compartments. Near the inlet the tracer residence time distribution curve analysis and Hydraulic Efficiency Indicators (HEIs) suggest poor disinfection performance. Further away from the inlet, the flow recovers to a two-dimensional flow and the HEIs improve until the exit of the tank. The computational results demonstrate good agreement between the predicted hydrodynamics and tracer transport with the corresponding experimental data. The numerical model is then employed to investigate the effects of up-scaling of laboratory model findings to a full-scale contact tank. Despite the Froude-Reynolds conflict the full-scale contact tank exhibits similar behaviour to the small-scale tank. The effect of the tank geometry on the disinfection efficiency is demonstrated, highlighting the negative impact of flow three-dimensionality on pathogen inactivation.
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Water Research, 2012
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Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy, 2010
Tidal stream systems make use of the kinetic energy of tidal movement to power turbines, in a sim... more Tidal stream systems make use of the kinetic energy of tidal movement to power turbines, in a similar manner to the way in which windmills extract energy from the wind. This method of renewable energy generation is gaining in popularity because of the high predictability of tides, the lower investment needed for tidal turbines, and the lower ecological impact, as compared with other schemes involving barrages or lagoons. It is generally considered that a mean spring peak tidal current of at least 2 m/s is required for tidal stream power to be worth exploiting. In the Severn Estuary, the peak tidal current exceeds 2 m/s, with a corresponding minimum depth of greater than 20 m, and it is thereby a potential location for tidal stream power. Previous studies cannot provide the detailed and precise distribution of tidal stream power in this estuary, and it has therefore been deemed appropriate to undertake a numerical model assessment of tidal stream energy resources in the Severn Estuar...
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Proceedings of the ICE - Water Management, 2014
Results of a computational fluid dynamics (CFD) study of flow, transport processes and pathogen i... more Results of a computational fluid dynamics (CFD) study of flow, transport processes and pathogen inactivation in contact tanks are presented. The three-dimensional numerical simulations are first validated using data from a previously completed laboratory experiment and velocity and conservative tracer transport data are available for comparison. The good agreement between CFD and experimental data confirms that the model reproduces accurately hydrodynamics and tracer transport processes. The analysis of the results reveals that the flow in the tank features extensive three-dimensionality, which is attributed to the current inlet configuration. Pathogen inactivation simulations show that complex flow in the tank affects the disinfection performance negatively. The potential for tank optimisation is examined by way of additional simulations featuring varying inlet designs, where it is shown that optimisation of inlet condition enhances the performance of the tank in terms of pathogen ...
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Coastal Engineering, 2011
Details are given herein of the refinement and application of a three-dimensional layer integrate... more Details are given herein of the refinement and application of a three-dimensional layer integrated numerical model to predict morphological changes in tidal basins. The solution of governing differential equations, which consist of the conservation of mass and momentum for the hydrodynamics, the transport equation for the suspended sediment fluxes and the sediment mass conservation equation for the bed level changes are carried out by the use of Alternating Direction Implicit (ADI) Finite Difference Method (FDM). The model includes ...
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Renewable Energy
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Renewable Energy, 2016
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Environmental Modeling & Assessment, 2016
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Applied Energy, 2016
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The performance of water disinfection facilities traditionally relies on Hydraulic Efficiency Ind... more The performance of water disinfection facilities traditionally relies on Hydraulic Efficiency Indicators (HEIs), extracted from experimentally derived Residence Time Distribution (RTD) curves. This approach has often been undertaken numerically through computational fluid dynamics (CFD) models, which can be calibrated to predict accurately RTDs, enabling the assessment of disinfection facilities prior to the construction of disinfection tanks. However, a significant drawback of the conventional efficiency methodology prescribed for disinfection tanks is associated with the respective indicators, as they are predominantly linked to the internal flow characteristics developed in the reactor, rather than the disinfection chemistry which should be optimized. In this study three-dimensional numerical models were refined to simulate the processes of chlorine decay, pathogen inactivation and the by-product formation in disinfection contact tanks (CTs). The main objective of this study was ...
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Papers by Roger A Falconer - Cardiff University