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G Tabor
College of Engineering, Mathematics and Physical Sciences, University of Exeter, Harrison Building, North Park Road, Exeter EX4 4QF, UK

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Journal article
Published: 06 August 2021 in Journal of Manufacturing and Materials Processing
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A critical challenge underpinning the adoption of Additive Manufacture (AM) as a technology is the postprocessing of manufactured components. For Powder Bed Fusion (PBF), this can involve the removal of powder from the interior of the component, often by vibrating the component to fluidise the powder to encourage drainage. In this paper, we develop and validate a computational model of the flow of metal powder suitable for predicting powder removal from such AM components. The model is a continuum Eulerian multiphase model of the powder including models for the granular temperature; the effect of vibration can be included through appropriate wall boundaries for this granular temperature. We validate the individual sub-models appropriate for AM metal powders by comparison with in-house and literature experimental results, and then apply the full model to a more complex geometry typical of an AM Heat Exchanger. The model is shown to provide valuable and accurate results at a fraction of the computational cost of a particle-based model.

ACS Style

Andrew Roberts; Recep Kahraman; Desi Bacheva; Gavin Tabor. Modelling of Powder Removal for Additive Manufacture Postprocessing. Journal of Manufacturing and Materials Processing 2021, 5, 86 .

AMA Style

Andrew Roberts, Recep Kahraman, Desi Bacheva, Gavin Tabor. Modelling of Powder Removal for Additive Manufacture Postprocessing. Journal of Manufacturing and Materials Processing. 2021; 5 (3):86.

Chicago/Turabian Style

Andrew Roberts; Recep Kahraman; Desi Bacheva; Gavin Tabor. 2021. "Modelling of Powder Removal for Additive Manufacture Postprocessing." Journal of Manufacturing and Materials Processing 5, no. 3: 86.

Preprint
Published: 29 June 2021
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A critical challenge underpinning the adoption of Additive Manufacture (AM) as a technology is the postprocessing of manufactured components. For Selective Laser Sintering (SLS) this can involve the removal of powder from the interior of the component, often by vibrating the component to fluidise the powder to encourage drainage. In this paper we develop and validate a computational model of the flow of metal powder suitable for predicting powder removal from such AM components. The model is a continuum Eulerian multiphase model of the powder including models for the granular temperature; the effect of vibration can be included through appropriate wall boundaries for this granular temperature. We validate the individual sub-models appropriate for AM metal powders by comparison with in-house and literature experimental results, and then apply the full model to a more complex geometry typical of an AM Heat Exchanger. The model is shown to provide valuable and accurate results at a fraction of the computational cost of a particle-based model.

ACS Style

Andrew Roberts; Recep Kahraman; Desi Bacheva; Gavin Tabor. Modelling of Powder Removal for Additive Manufacture Postprocessing. 2021, 1 .

AMA Style

Andrew Roberts, Recep Kahraman, Desi Bacheva, Gavin Tabor. Modelling of Powder Removal for Additive Manufacture Postprocessing. . 2021; ():1.

Chicago/Turabian Style

Andrew Roberts; Recep Kahraman; Desi Bacheva; Gavin Tabor. 2021. "Modelling of Powder Removal for Additive Manufacture Postprocessing." , no. : 1.

Journal article
Published: 22 April 2021 in Computer Methods in Applied Mechanics and Engineering
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The capability to incorporate moving geometric features within models for complex simulations is a common requirement in many fields. Fluid mechanics within aeronautical applications, for example, routinely feature rotating (e.g. turbines, wheels and fan blades) or sliding components (e.g. in compressor or turbine cascade simulations). With an increasing trend towards the high-fidelity modelling of these cases, in particular combined with the use of high-order discontinuous Galerkin methods, there is therefore a requirement to understand how different numerical treatments of the interfaces between the static mesh and the sliding/rotating part impact on overall solution quality. In this article, we compare two different approaches to handle this non-conformal interface. The first is the so-called mortar approach, where flux integrals along edges are split according to the positioning of the non-conformal grid. The second is a less-documented point-to-point interpolation method, where the interior and exterior quantities for flux evaluations are interpolated from elements lying on the opposing side of the interface. Although the mortar approach has significant advantages in terms of its numerical properties, in that it preserves the local conservation properties of DG methods, in the context of complex 3D meshes it poses notable implementation difficulties which the point-to-point method handles more readily. In this paper we examine the numerical properties of each method, focusing not only on observing convergence orders for smooth solutions, but also how each method performs in under-resolved simulations of linear and nonlinear hyperbolic problems, to inform the use of these methods in implicit large-eddy simulations.

ACS Style

Edward Laughton; Gavin Tabor; David Moxey. A comparison of interpolation techniques for non-conformal high-order discontinuous Galerkin methods. Computer Methods in Applied Mechanics and Engineering 2021, 381, 113820 .

AMA Style

Edward Laughton, Gavin Tabor, David Moxey. A comparison of interpolation techniques for non-conformal high-order discontinuous Galerkin methods. Computer Methods in Applied Mechanics and Engineering. 2021; 381 ():113820.

Chicago/Turabian Style

Edward Laughton; Gavin Tabor; David Moxey. 2021. "A comparison of interpolation techniques for non-conformal high-order discontinuous Galerkin methods." Computer Methods in Applied Mechanics and Engineering 381, no. : 113820.

Research article
Published: 06 March 2021 in Optimization and Engineering
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The draft tube of a hydraulic turbine plays an important role for the efficiency and power characteristics of the overall system. The shape of the draft tube affects its performance, resulting in an increasing need for data-driven optimisation for its design. In this paper, shape optimisation of an elbow-type draft tube is undertaken, combining Computational Fluid Dynamics and a multi-objective Bayesian methodology. The chosen design objectives were to maximise pressure recovery, and minimise wall-frictional losses along the geometry. The design variables were chosen to explore potential new designs, using a series of subdivision-curves and splines on the inflow cone, outer-heel, and diffuser. The optimisation run was performed under part-load for the Kaplan turbine. The design with the lowest energy-loss identified on the Pareto-front was found to have a straight tapered diffuser, chamfered heel, and a convex inflow cone. Analysis of the performance quantities showed the typically used energy-loss factor and pressure recovery were highly correlated in cases of constant outflow cross-sections, and therefore unsuitable for use of multi-objective optimisation. Finally, a number of designs were tested over a range of discharges. From this it was found that reducing the heel size increased the efficiency over a wider operating range.

ACS Style

S. J. Daniels; A. A. M. Rahat; G. R. Tabor; J. E. Fieldsend; R. M. Everson. Application of multi-objective Bayesian shape optimisation to a sharp-heeled Kaplan draft tube. Optimization and Engineering 2021, 1 -28.

AMA Style

S. J. Daniels, A. A. M. Rahat, G. R. Tabor, J. E. Fieldsend, R. M. Everson. Application of multi-objective Bayesian shape optimisation to a sharp-heeled Kaplan draft tube. Optimization and Engineering. 2021; ():1-28.

Chicago/Turabian Style

S. J. Daniels; A. A. M. Rahat; G. R. Tabor; J. E. Fieldsend; R. M. Everson. 2021. "Application of multi-objective Bayesian shape optimisation to a sharp-heeled Kaplan draft tube." Optimization and Engineering , no. : 1-28.

Journal article
Published: 01 February 2021 in Journal of Marine Science and Engineering
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Computational fluid dynamics (CFD) modelling of wave interaction with thin perforated structures is of interest in a range of engineering applications. When large-scale effects such as forces and the overall flow behaviour are of interest, a microstructural resolution of the perforated geometry can be excessive or prohibitive in terms of computational cost. More efficiently, a thin porous structure can be represented by its macro-scale effects by means of a quadratic momentum source or pressure-drop respectively. In the context of regular wave interaction with thin porous structures and within an incompressible, two-phase Navier–Stokes and volume-of-fluid framework (based on interFoam of OpenFOAM®), this work investigates porosity representation as a porous surface with a pressure-jump condition and as volumetric isotropic and anisotropic porous media. Potential differences between these three types of macro-scale porosity implementations are assessed in terms of qualitative flow visualizations, velocity profiles along the water column, the wave elevation near the structures and the horizontal force on the structures. The comparison shows that all three types of implementation are capable of reproducing large-scale effects of the wave-structure interaction and that the differences between all obtained results are relatively small. It was found that the isotropic porous media implementation is numerically the most stable and requires the shortest computation times. The pressure-jump implementation requires the smallest time steps for stability and thus the longest computation times. This is likely due to the spurious local velocities at the air-water interface as a result of the volume-of-fluid interface capturing method combined with interFoam’s segregated pressure-velocity coupling algorithm. This paper provides useful insights and recommendations for effective macro-scale modelling of thin porous structures.

ACS Style

Anna Feichtner; Ed Mackay; Gavin Tabor; Philipp Thies; Lars Johanning. Comparison of Macro-Scale Porosity Implementations for CFD Modelling of Wave Interaction with Thin Porous Structures. Journal of Marine Science and Engineering 2021, 9, 150 .

AMA Style

Anna Feichtner, Ed Mackay, Gavin Tabor, Philipp Thies, Lars Johanning. Comparison of Macro-Scale Porosity Implementations for CFD Modelling of Wave Interaction with Thin Porous Structures. Journal of Marine Science and Engineering. 2021; 9 (2):150.

Chicago/Turabian Style

Anna Feichtner; Ed Mackay; Gavin Tabor; Philipp Thies; Lars Johanning. 2021. "Comparison of Macro-Scale Porosity Implementations for CFD Modelling of Wave Interaction with Thin Porous Structures." Journal of Marine Science and Engineering 9, no. 2: 150.

Journal article
Published: 26 November 2020 in Fluids
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A common challenge faced by engineers in the hydraulic industry is the formation of free surface vortices at pump and power intakes. This undesirable phenomenon which sometimes entrains air could result in several operational problems: noise, vibration, cavitation, surging, structural damage to turbines and pumps, energy losses, efficiency losses, etc. This paper investigates the numerical simulation of an experimentally observed air-core vortex at an intake using the LTSInterFoam solver in OpenFOAM. The solver uses local time-stepping integration. In simulating the air-core vortex, the standard k − ε, realizable k − ε, renormalization group (RNG) k − ε and the shear stress transport (SST) k − ω models were used. The free surface was modelled using the volume of fluid (VOF) model. The simulation was validated using a set of analytical models and experimental data. The SST k − ω model provided the best results compared to the other turbulence models. The study was extended to simulate the effect of installing an anti-vortex device on the formation of a free surface vortex. The LTSInterFoam solver proved to be a reliable solver for the steady state simulation of a free surface vortex in OpenFOAM.

ACS Style

Martin Kyereh Domfeh; Samuel Gyamfi; Mark Amo-Boateng; Robert Andoh; Eric Antwi Ofosu; Gavin Tabor. Numerical Simulation of an Air-Core Vortex and Its Suppression at an Intake Using OpenFOAM. Fluids 2020, 5, 221 .

AMA Style

Martin Kyereh Domfeh, Samuel Gyamfi, Mark Amo-Boateng, Robert Andoh, Eric Antwi Ofosu, Gavin Tabor. Numerical Simulation of an Air-Core Vortex and Its Suppression at an Intake Using OpenFOAM. Fluids. 2020; 5 (4):221.

Chicago/Turabian Style

Martin Kyereh Domfeh; Samuel Gyamfi; Mark Amo-Boateng; Robert Andoh; Eric Antwi Ofosu; Gavin Tabor. 2020. "Numerical Simulation of an Air-Core Vortex and Its Suppression at an Intake Using OpenFOAM." Fluids 5, no. 4: 221.

Journal article
Published: 11 March 2020 in Fluids
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The continuous adjoint approach is a technique for calculating the sensitivity of a flow to changes in input parameters, most commonly changes of geometry. Here we present for the first time the mathematical derivation of the adjoint system for multiphase flow modeled by the commonly used drift flux equations, together with the adjoint boundary conditions necessary to solve a generic multiphase flow problem. The objective function is defined for such a system, and specific examples derived for commonly used settling velocity formulations such as the Takacs and Dahl models. We also discuss the use of these equations for a complete optimisation process.

ACS Style

Shenan Grossberg; Daniel S. Jarman; Gavin R. Tabor. Derivation of the Adjoint Drift Flux Equations for Multiphase Flow. Fluids 2020, 5, 31 .

AMA Style

Shenan Grossberg, Daniel S. Jarman, Gavin R. Tabor. Derivation of the Adjoint Drift Flux Equations for Multiphase Flow. Fluids. 2020; 5 (1):31.

Chicago/Turabian Style

Shenan Grossberg; Daniel S. Jarman; Gavin R. Tabor. 2020. "Derivation of the Adjoint Drift Flux Equations for Multiphase Flow." Fluids 5, no. 1: 31.

Journal article
Published: 29 January 2020 in Sustainability
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The rise in the human population, its density and scarcity of resources require cost-effective solutions for sustainable energy and water resources. Smart and sustainable agriculture is one important factor for future green cities to tackle climate change as a cost-effective solution to save energy and water. However, greenhouses (GH) require consistent ventilation due to their internal temperatures, and this can be an energy-intensive operation. Therefore, it is necessary to analyse the potential factors involved. In this study, the effect of vent configuration of a mono-span greenhouse with roof and side vents at low wind speeds was investigated using computational fluid dynamics (CFD). The validated simulations were then performed on different models to analyse the effects of the vents’ locations on the ventilation requirements. The side vents were found to contribute most to the ventilation. The position of the side vent was found to affect the convection loop in the greenhouse and the air velocity at the plant level. The humidity was shown to be highest under the windward side vent. The roof vent was found to affect the temperature and air velocity in the roof of the greenhouse but had very little effect on the distributions at the plant level.

ACS Style

Mohammad Akrami; Akbar A. Javadi; Matthew J. Hassanein; Raziyeh Farmani; Mahdieh Dibaj; Gavin R. Tabor; Abdelazim Negm. Study of the Effects of Vent Configuration on Mono-Span Greenhouse Ventilation Using Computational Fluid Dynamics. Sustainability 2020, 12, 986 .

AMA Style

Mohammad Akrami, Akbar A. Javadi, Matthew J. Hassanein, Raziyeh Farmani, Mahdieh Dibaj, Gavin R. Tabor, Abdelazim Negm. Study of the Effects of Vent Configuration on Mono-Span Greenhouse Ventilation Using Computational Fluid Dynamics. Sustainability. 2020; 12 (3):986.

Chicago/Turabian Style

Mohammad Akrami; Akbar A. Javadi; Matthew J. Hassanein; Raziyeh Farmani; Mahdieh Dibaj; Gavin R. Tabor; Abdelazim Negm. 2020. "Study of the Effects of Vent Configuration on Mono-Span Greenhouse Ventilation Using Computational Fluid Dynamics." Sustainability 12, no. 3: 986.

Articles
Published: 20 November 2019 in International Journal of Computational Fluid Dynamics
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Additive Manufacturing (AM) is a rapidly developing new technology which allows the manufacture of arbitrarily complex geometries, and which is likely to transform heat exchanger design. To drive this transformation we need to develop computer modelling techniques to model fluid flow, heat exchange and phase change in arbitrarily complex domains, such as can be manufactured using AM. The present work aims to develop a computational fluid dynamics (CFD) model for heat transfer and phase change, robust enough to model compact AM heat exchangers for automotive fuel cell application. The hydrodynamics of the two-phase flow is captured via the Volume Of Fluid (VOF) approach, coupled with a Level Set method in order to capture the sharp interface between liquid and vapour in laminar film condensation. The Stefan problem is used to show the improvement of the interface tracking with LS-VOF against VOF approach. The resulting complete condensation model is applied for the first time for a complex AM geometry and validated against experimental data.

ACS Style

R. Kahraman; D. Bacheva; A. Schmieder; G. R. Tabor. Coupling of volume of fluid and level set methods in condensing heat transfer simulations. International Journal of Computational Fluid Dynamics 2019, 34, 25 -38.

AMA Style

R. Kahraman, D. Bacheva, A. Schmieder, G. R. Tabor. Coupling of volume of fluid and level set methods in condensing heat transfer simulations. International Journal of Computational Fluid Dynamics. 2019; 34 (1):25-38.

Chicago/Turabian Style

R. Kahraman; D. Bacheva; A. Schmieder; G. R. Tabor. 2019. "Coupling of volume of fluid and level set methods in condensing heat transfer simulations." International Journal of Computational Fluid Dynamics 34, no. 1: 25-38.

Journal article
Published: 30 August 2019 in Energies
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In the food industry, heating and cooling are key processes where CFD can play an important role in improving quality, productivity and reducing energy costs. Cooling products after baking is crucial for storage and transportation; the product has to be cooled efficiently to a specified temperature (often to fulfill regulatory requirements) whilst preserving its quality. This study involves the analysis of spiral cooling refrigerators used in cooling food products, in this case, Cornish Pasties. Three separate sets of CFD models were developed and validated against experimental data taken in the laboratory and measurements taken in use in industry. In the first set of models a full CFD model was developed of a refrigeration spiral including the pasties, and used to study the heat transfer from the products to the air. Further simulations were carried out on individual pasties to explore the pasty cooling and heat transfer to the air in more detail, with the pasty geometry being determined from MRI scans. In the final set of simulations, Image Based Meshing (IBM) was used to determine the interior structure of the pasty and develop a full heat conduction model of the interior, which was compared with separate laboratory experiments using jets of cold air to cool the pasty. In all cases, good agreement was obtained between the CFD results and experimental data, whilst the CFD simulations provide valuable information about the air flows and cooling in the industrial system.

ACS Style

A. Khenien; A. Benattayallah; G. Tabor. CFD Simulation of an Industrial Spiral Refrigeration System. Energies 2019, 12, 3358 .

AMA Style

A. Khenien, A. Benattayallah, G. Tabor. CFD Simulation of an Industrial Spiral Refrigeration System. Energies. 2019; 12 (17):3358.

Chicago/Turabian Style

A. Khenien; A. Benattayallah; G. Tabor. 2019. "CFD Simulation of an Industrial Spiral Refrigeration System." Energies 12, no. 17: 3358.

Review
Published: 25 August 2019 in Energies
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Computational Fluid Dynamics (CFD) has numerous applications in the field of energy research, in modelling the basic physics of combustion, multiphase flow and heat transfer; and in the simulation of mechanical devices such as turbines, wind wave and tidal devices, and other devices for energy generation. With the constant increase in available computing power, the fidelity and accuracy of CFD simulations have constantly improved, and the technique is now an integral part of research and development. In the past few years, the development of multiscale methods has emerged as a topic of intensive research. The variable scales may be associated with scales of turbulence, or other physical processes which operate across a range of different scales, and often lead to spatial and temporal scales crossing the boundaries of continuum and molecular mechanics. In this paper, we present a short review of multiscale CFD frameworks with potential applications to energy problems.

ACS Style

Dimitris Drikakis; Michael Frank; Gavin Tabor. Multiscale Computational Fluid Dynamics. Energies 2019, 12, 3272 .

AMA Style

Dimitris Drikakis, Michael Frank, Gavin Tabor. Multiscale Computational Fluid Dynamics. Energies. 2019; 12 (17):3272.

Chicago/Turabian Style

Dimitris Drikakis; Michael Frank; Gavin Tabor. 2019. "Multiscale Computational Fluid Dynamics." Energies 12, no. 17: 3272.

Articles
Published: 09 August 2019 in International Journal of Computational Fluid Dynamics
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An approach for shape optimisation of the flow through a diffuser is presented in this work. This multi-objective problem focuses on maximising the diffuser performance by simultaneously increasing the static pressure recovery across the geometry and the flow uniformity at the outflow. The hydrodynamic analysis of the geometry was conducted using the Computational Fluid Dynamics (CFD) software OpenFOAM, while a recently proposed multi-objective Bayesian approach was used for optimisation. The CFD and Bayesian methodology have been combined for fully automated operation using a Python-based framework. The proposed design parameterisation focuses on reshaping the diffuser in the expansion region. Catmull–Clark subdivision curves were employed to represent the shape of the diffuser wall; the influence of the number of control points (design points) for the curves on the optimum design was investigated. The optimal designs exhibit a reasonable performance improvement compared with the base design.

ACS Style

S. J. Daniels; A. A. M. Rahat; G. R. Tabor; J. E. Fieldsend; R. M. Everson. Automated shape optimisation of a plane asymmetric diffuser using combined Computational Fluid Dynamic simulations and multi-objective Bayesian methodology. International Journal of Computational Fluid Dynamics 2019, 33, 256 -271.

AMA Style

S. J. Daniels, A. A. M. Rahat, G. R. Tabor, J. E. Fieldsend, R. M. Everson. Automated shape optimisation of a plane asymmetric diffuser using combined Computational Fluid Dynamic simulations and multi-objective Bayesian methodology. International Journal of Computational Fluid Dynamics. 2019; 33 (6-7):256-271.

Chicago/Turabian Style

S. J. Daniels; A. A. M. Rahat; G. R. Tabor; J. E. Fieldsend; R. M. Everson. 2019. "Automated shape optimisation of a plane asymmetric diffuser using combined Computational Fluid Dynamic simulations and multi-objective Bayesian methodology." International Journal of Computational Fluid Dynamics 33, no. 6-7: 256-271.

Journal article
Published: 08 August 2019 in Journal of Hydraulic Research
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ACS Style

Recep Kahraman; Matthew Riella; Gavin R. Tabor; Mohsen Ebrahimi; Slobodan Djordjević; Prakash Kripakaran. Prediction of flow around a sharp-nosed bridge pier: influence of the Froude number and free-surface variation on the flow field. Journal of Hydraulic Research 2019, 58, 582 -593.

AMA Style

Recep Kahraman, Matthew Riella, Gavin R. Tabor, Mohsen Ebrahimi, Slobodan Djordjević, Prakash Kripakaran. Prediction of flow around a sharp-nosed bridge pier: influence of the Froude number and free-surface variation on the flow field. Journal of Hydraulic Research. 2019; 58 (4):582-593.

Chicago/Turabian Style

Recep Kahraman; Matthew Riella; Gavin R. Tabor; Mohsen Ebrahimi; Slobodan Djordjević; Prakash Kripakaran. 2019. "Prediction of flow around a sharp-nosed bridge pier: influence of the Froude number and free-surface variation on the flow field." Journal of Hydraulic Research 58, no. 4: 582-593.

Chapter
Published: 25 January 2019 in OpenFOAM®
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Tidal estuaries represent a significant and accessible source of renewable energy for modern society. The regular nature of the tides makes this a valuable resource to exploit. Tidal turbines that extract energy from tidal currents would be one way to do this. The shallow nature of estuaries suggests that these would need to be low power units linked together in large farms, and the modelling and optimisation of such farms of turbines is a significant challenge. In this chapter, I report on a major research effort to model a possible turbine, the AquaScientific Lift/Drag turbine, and the development from this of a simplified CFD model, the Immersed Body Force method, to allow for simulation of small arrays. Following from this, I report on the development of surrogate modelling techniques to allow the prediction of outputs from larger arrays and optimisation using Genetic Algorithm techniques.

ACS Style

G. R. Tabor. CFD Analysis and Optimisation of Tidal Turbine Arrays Using OpenFOAM $$^{\textregistered }$$. OpenFOAM® 2019, 51 -64.

AMA Style

G. R. Tabor. CFD Analysis and Optimisation of Tidal Turbine Arrays Using OpenFOAM $$^{\textregistered }$$. OpenFOAM®. 2019; ():51-64.

Chicago/Turabian Style

G. R. Tabor. 2019. "CFD Analysis and Optimisation of Tidal Turbine Arrays Using OpenFOAM $$^{\textregistered }$$." OpenFOAM® , no. : 51-64.

Journal article
Published: 01 December 2018 in Journal of Hydraulic Engineering
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Previous experimental research on the effects of debris on pier scour has focused primarily on circular and rectangular piers with debris present just under flow free surface. Debris-induced scour around sharp-nose piers, which are typical of masonry bridge piers, and the effect of debris elevation on pier scour have seldom been studied before. This paper aims to fill this knowledge gap. It presents results from flume experiments investigating scour around a sharp-nose pier under shallow flow conditions with angle of attack relative to the pier being zero. Uniform sand is used as bed material. Debris is modeled as stationary and extending only upstream of the pier. Three simplified debris geometries (cylinder, half-pyramid, and plate) are studied. Results show that scour depth decreases as debris gets closer to the bed with maximum scour depth occurring when debris is located just under the flow free surface. Interestingly, scour depths produced by debris in shallow flow are observed to be comparable to those produced by deep flow in the absence of debris. This finding highlights the importance of monitoring debris accumulation at bridges in nonflood conditions. Results also show that the volume of the scour hole around a pier increases quadratically with maximum scour depth. This information is useful for postflood scour remedial works. Lastly, the collected laboratory measurements are used to compare four popular equations for scour estimation on their ability to predict debris-induced scour. The Colorado State University (CSU) equation is found to offer the most accurate predictions.

ACS Style

Mohsen Ebrahimi; Prakash Kripakaran; Dušan M. Prodanović; Recep Kahraman; Matthew Riella; Gavin Tabor; Scott Arthur; Slobodan Djordjević. Experimental Study on Scour at a Sharp-Nose Bridge Pier with Debris Blockage. Journal of Hydraulic Engineering 2018, 144, 04018071 .

AMA Style

Mohsen Ebrahimi, Prakash Kripakaran, Dušan M. Prodanović, Recep Kahraman, Matthew Riella, Gavin Tabor, Scott Arthur, Slobodan Djordjević. Experimental Study on Scour at a Sharp-Nose Bridge Pier with Debris Blockage. Journal of Hydraulic Engineering. 2018; 144 (12):04018071.

Chicago/Turabian Style

Mohsen Ebrahimi; Prakash Kripakaran; Dušan M. Prodanović; Recep Kahraman; Matthew Riella; Gavin Tabor; Scott Arthur; Slobodan Djordjević. 2018. "Experimental Study on Scour at a Sharp-Nose Bridge Pier with Debris Blockage." Journal of Hydraulic Engineering 144, no. 12: 04018071.

Journal article
Published: 01 September 2017 in International Journal of Marine Energy
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ACS Style

Miriam García-Oliva; Slobodan Djordjević; Gavin R. Tabor. The impacts of tidal turbines on water levels in a shallow estuary. International Journal of Marine Energy 2017, 19, 177 -197.

AMA Style

Miriam García-Oliva, Slobodan Djordjević, Gavin R. Tabor. The impacts of tidal turbines on water levels in a shallow estuary. International Journal of Marine Energy. 2017; 19 ():177-197.

Chicago/Turabian Style

Miriam García-Oliva; Slobodan Djordjević; Gavin R. Tabor. 2017. "The impacts of tidal turbines on water levels in a shallow estuary." International Journal of Marine Energy 19, no. : 177-197.

Journal article
Published: 01 February 2017 in Renewable Energy
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ACS Style

Miriam Garcia-Oliva; Slobodan Djordjević; Gavin R. Tabor. The influence of channel geometry on tidal energy extraction in estuaries. Renewable Energy 2017, 101, 514 -525.

AMA Style

Miriam Garcia-Oliva, Slobodan Djordjević, Gavin R. Tabor. The influence of channel geometry on tidal energy extraction in estuaries. Renewable Energy. 2017; 101 ():514-525.

Chicago/Turabian Style

Miriam Garcia-Oliva; Slobodan Djordjević; Gavin R. Tabor. 2017. "The influence of channel geometry on tidal energy extraction in estuaries." Renewable Energy 101, no. : 514-525.

Journal article
Published: 01 December 2016 in International Journal of Marine Energy
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Highlights•Experimental work conducted on a scaled tidal turbine to measure flow characteristics•CFD calculations are performed to replicate the experimental conditions•Comparisons showed good match of the wake profiles particularly downstream of the turbine•Few inaccuracies observed upstream of the turbine indicating some of the drawbacks of the CFD model AbstractThis paper investigates the accuracy of the Computational Fluid Dynamics (CFD) based Immersed Body Force (IBF) turbine modelling method for predicting the flow characteristics of a Momentum-Reversal-Lift type of tidal turbine. This empirically-based CFD model has been developed based on the actuator disc method enhanced with additional features to mimic the effect of the complex blade motion on the downstream wake, without the high computational costs of explicitly modelling the dynamic blade motion. The model has been calibrated against the flow characteristics data obtained from experiment and found to perform well, although there are few inconsistencies in the flow patterns which show some of the limitations of the IBF model compared to a full dynamic blade motion simulation. However, given the complexity and computational cost of modelling the detailed blade motion the limitations of the IBF model are acceptable and will be useful especially for optimisation of arrays of devices where there is a significant computational demand.

ACS Style

Mulualem G. Gebreslassie; Stephanie O. Sanchez; Gavin R. Tabor; Michael R. Belmont; Tom Bruce; Grégory S. Payne; Ian Moon. Experimental and CFD analysis of the wake characteristics of tidal turbines. International Journal of Marine Energy 2016, 16, 209 -219.

AMA Style

Mulualem G. Gebreslassie, Stephanie O. Sanchez, Gavin R. Tabor, Michael R. Belmont, Tom Bruce, Grégory S. Payne, Ian Moon. Experimental and CFD analysis of the wake characteristics of tidal turbines. International Journal of Marine Energy. 2016; 16 ():209-219.

Chicago/Turabian Style

Mulualem G. Gebreslassie; Stephanie O. Sanchez; Gavin R. Tabor; Michael R. Belmont; Tom Bruce; Grégory S. Payne; Ian Moon. 2016. "Experimental and CFD analysis of the wake characteristics of tidal turbines." International Journal of Marine Energy 16, no. : 209-219.

Journal article
Published: 01 September 2016 in Applied Mathematical Modelling
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Accurate prediction of the air-entrainment process in air-water two-phase turbulent flows is one of the most computationally challenging subjects under current investigation in hydraulic engineering. An ideal numerical model for air-entrainment needs to be accurate and fast in the definition of a macroscopic interface and simultaneously precise enough to take into account the formation of bubbles through the free-surface, their transport and their natural interactions: bubble-bubble and bubble-fluid. The problem is made more complex by the strong coupling between mesh and solution exhibited by interface capturing schemes which are commonly used for such problems. This paper examines numerical and modelling aspects of the entrainment process for two canonical cases; the 2D dam break and 3D circular plunging jet cases. We start by investigating the capacities of a Volume-of-Fluid based model to detect the free-surface and predict the velocities inside the water phase, examining the effect of coarsening and refining the mesh on the prediction of the interface location. A reformulated explicit term is used to detect bubble formation and air-entrainment at the free-surface, without the need of a calibration process and adapted to run together with Volume-of-Fluid models. The results obtained with this new approach are further compared with similar cases in the literature in terms of bubble formation and free-surface wave’s amplitude. The correct definition of the free-surface was found to be strongly dependent on the mesh refinement in a way that has very significant implications for the development of air-entrainment modelling.

ACS Style

Pedro Lopes; Gavin Tabor; Rita Carvalho; Jorge Leandro. Explicit calculation of natural aeration using a Volume-of-Fluid model. Applied Mathematical Modelling 2016, 40, 7504 -7515.

AMA Style

Pedro Lopes, Gavin Tabor, Rita Carvalho, Jorge Leandro. Explicit calculation of natural aeration using a Volume-of-Fluid model. Applied Mathematical Modelling. 2016; 40 (17-18):7504-7515.

Chicago/Turabian Style

Pedro Lopes; Gavin Tabor; Rita Carvalho; Jorge Leandro. 2016. "Explicit calculation of natural aeration using a Volume-of-Fluid model." Applied Mathematical Modelling 40, no. 17-18: 7504-7515.

Conference paper
Published: 29 August 2016 in Scour and Erosion
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Scour and Erosionincludes four keynote lectures from world leading researchers cutting across the themes of scour and erosion, together with 132 peer-reviewed papers from 34 countries, covering the principal themes of: - internal erosion- sediment transport- grain scale to continuum scale- advanced numerical modelling of scour and erosion- terrestrial scour and erosion- river and estuarine erosion including scour around structures, and- management of scour/erosion and sediment, including hazard management and sedimentation in dams and reservoirs. Scour and Erosionis ideal for researchers and industry working at the forefront of scour and erosion, and has applications in both the freshwater and marine environments. Scour and Erosionincludes four keynote lectures from world leading researchers cutting across the themes of scour and erosion, together with 132 peer-reviewed papers from 34 countries, covering the principal themes of: - internal erosion- sediment transport- grain scale to continuum scale- advanced numerical modelling of scour and erosion- terrestrial scour and erosion- river and estuarine erosion including scour around structures, and- management of scour/erosion and sediment, including hazard management and sedimentation in dams and reservoirs. Scour and Erosionis ideal for researchers and industry working at the forefront of scour and erosion, and has applications in both the freshwater and marine environments. Scour and Erosionincludes four keynote lectures from world leading researchers cutting across the themes of scour and erosion, together with 132 peer-reviewed papers from 34 countries, covering the principal themes of: - internal erosion- sediment transport- grain scale to continuum scale- advanced numerical modelling of scour and erosion- terrestrial scour and erosion- river and estuarine erosion including scour around structures, and- management of scour/erosion and sediment, including hazard management and sedimentation in dams and reservoirs. Scour and Erosionis ideal for researchers and industry working at the forefront of scour and erosion, and has applications in both the freshwater and marine environments. Scour and Erosionincludes four keynote lectures from world leading researchers cutting across the themes of scour and erosion, together with 132 peer-reviewed papers from 34 countries, covering the principal themes of: - internal erosion- sediment transport- grain scale to continuum scale- advanced numerical modelling of scour and erosion- terrestrial scour and erosion- river and estuarine erosion including scour around structures, and- management of scour/erosion and sediment, including hazard management and sedimentation in dams and reservoirs. Scour and Erosionis ideal for researchers and industry working at the forefront of scour and erosion, and has applications in both the freshwater and marine environments. Scour and Erosionincludes four keynote lectures from world leading researchers cutting across the themes of scour and erosion, together with 132 peer-reviewed papers from 34 countries, covering the principal themes of: - internal erosion- sediment transport- grain scale to continuum scale- advanced numerical modelling of scour and erosion- terrestrial scour and erosion- river and estuarine erosion including scour around structures, and- management of scour/erosion and sediment, including hazard management and sedimentation in dams and reservoirs. Scour and Erosionis ideal for researchers and industry working at the forefront of scour and erosion, and has applications in both the freshwater and marine environments. Scour and Erosionincludes four keynote lectures from world leading researchers cutting across the themes of scour and erosion, together with 132 peer-reviewed papers from 34 countries, covering the principal themes of: - internal erosion- sediment transport- grain scale to continuum scale- advanced numerical modelling of scour and erosion- terrestrial scour and erosion- river and estuarine erosion including scour around structures, and- management of scour/erosion and sediment, including hazard management and sedimentation in dams and reservoirs. Scour and Erosionis ideal for researchers and industry working at the forefront of scour and erosion, and has applications in both the freshwater and marine environments.

ACS Style

M Ebrahimi; P Kripakaran; S Djordjević; G Tabor; R Kahraman; D Prodanović; S Arthur. Hydrodynamic effects of debris blockage and scour on masonry bridges: Towards experimental modelling. Scour and Erosion 2016, 1 .

AMA Style

M Ebrahimi, P Kripakaran, S Djordjević, G Tabor, R Kahraman, D Prodanović, S Arthur. Hydrodynamic effects of debris blockage and scour on masonry bridges: Towards experimental modelling. Scour and Erosion. 2016; ():1.

Chicago/Turabian Style

M Ebrahimi; P Kripakaran; S Djordjević; G Tabor; R Kahraman; D Prodanović; S Arthur. 2016. "Hydrodynamic effects of debris blockage and scour on masonry bridges: Towards experimental modelling." Scour and Erosion , no. : 1.