David Hargreaves

David Hargreaves
University of Nottingham | Notts · Department of Civil Engineering

Doctor of Philosophy

About

105
Publications
36,221
Reads
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1,560
Citations
Citations since 2016
17 Research Items
888 Citations
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2016201720182019202020212022020406080100120140
2016201720182019202020212022020406080100120140
2016201720182019202020212022020406080100120140

Publications

Publications (105)
Conference Paper
Full-text available
A detailed rheological characterisation of Recycled Tyre Rubber Modified Bitumen's (RTR-MB) is of paramount importance for their modelling, formulation, processing and performance. Nevertheless, adding crumb rubber to the base bitumen, further than improving the material characteristics can also represent an issue for rheologists. In fact, due to t...
Article
Full-text available
Modified bituminous binders allow asphalt technologists to design asphalt mixtures with superior performance. However, several recent studies highlighted that due to the complexity of these material, their characterisation can be challenging since common procedures used to characterise neat bitumen might not be adequate. For instance, during high t...
Article
Full-text available
Computational Fluid Dynamics (CFD) is increasingly used to model particulate dispersion in situations where Gaussian Dispersion models are inappropriate or inaccurate. However, there is evidence which indicates that many CFD models under-predict lateral plume spread. This paper aims to address this by implementing a strategy which incorporates wind...
Chapter
This chapter is split into two broad sections. The first deals with lakes – more specifically their categorization, their characteristics, and the quality of their water. The chapter briefly presents the seven main different formation processes, as tectonic activity, volcanic activity, glacial activity, fluvial action, Aeolic action, anthropogenic...
Chapter
This chapter presents an extensive background on Lake Manzala, Egypt, in the form of a literature review. It covers the lake’s physical, chemical, and biological characteristics to date. In addition, the main challenges for the lake water body are land reclamation, nutrient enrichment, and pollution, especially from the Bahr El-Baqar drain. In addi...
Chapter
This chapter presents a review of previous studies related to the numerical modelling of the hydrodynamics of coastal lakes with emphasis on Egyptian coastal lakes. Also, related applications, such as water quality management and sediment transport scenarios in lakes, are presented. The focus is primarily on existing, well-established, numerical mo...
Article
Considered to be representative of a generic bridge deck geometry and characterised by a highly unsteady flow field, the 5:1 rectangular cylinder has been the main case study in a number of studies including the “Benchmark on the Aerodynamics of a Rectangular 5:1 Cylinder” (BARC). There are still a number of limitations in the knowledge of (i) the...
Article
Full-text available
This paper presents an evaluation of a buoyancy-modified k−ε dust dispersion model for predicting fugitive dust deposition from a surface quarry. The dust clouds are modelled as volumetric emissions and their dispersion simulated by coupling the flow-field with stochastic tracking of the particulates. The coefficients of the turbulence model are mo...
Conference Paper
Full-text available
The latest generation of super-long suspension bridge decks are designed to avoid being excited by the wind. The classic failure of the Tacoma Narrows Bridge in the USA was a wake-up call; many studies since have concentrated on the aeroelasticity of various cross-sections. As a generic bridge deck geometry, the 5:1 rectangular cylinder has attract...
Conference Paper
Full-text available
The latest generation of super-long suspension bridge decks are designed to avoid being excited by the wind. The classic failure of the Tacoma Narrows Bridge in the USA was a wake-up call; many studies since have concentrated on the aeroelasticity of various cross-sections. As a generic bridge deck geometry, the 5:1 rectangular cylinder has attract...
Article
Full-text available
Multi-phase materials are common in several fields of engineering and rheological measurements are intensively adopted for their development and quality control. Unfortunately, due to the complexity of these materials, accurate measurements can be challenging. This is the case of bitumen-rubber blends used in civil engineering as binders for severa...
Article
Full-text available
The development and validation of a grid-based pore-scale numerical modelling methodology applied to five different commercial metal foam samples is described. The 3-D digital representation of the foam geometry was obtained by the use of X-ray microcomputer tomography scans, and macroscopic properties such as porosity, specific surface and pore si...
Article
Full-text available
The rise of Taylor bubbles through expansions in vertical pipes is modelled using Computational Fluid Dynamics. The predictions from the models are compared against existing experimental work and show good agreement, both quantitatively and qualitatively. Many workers, including the present work, find that, as the bubble passes through the expansio...
Article
Full-text available
In this study, computational fluid dynamics (CFD) modeling is used to simulate Taylor bubbles rising in vertical pipes. Experiments indicate that in large diameter (0.29?m) pipes for an air?water system, the bubbles can rise in a oscillatory manner, depending on the method of air injection. The CFD models are able to capture this oscillatory behavi...
Conference Paper
Full-text available
In this paper, a wind tunnel study is described focusing on analysing the pressure distribution and correlation around both static and dynamic 5:1 rectangular cylinders in smooth and turbulent flow. Results from the static tests highlighted the significant influences of the turbulence on the surface pressure distribution. For the dynamic section, t...
Conference Paper
Full-text available
This paper describes the development and testing of a numerical model, based around the Large Eddy Simulation model, of a flexible 5:1 rectangular cylinder. We report on the vortex-induced vibration (VIV) of the bending cylinder, which is an analogue for a flexible bridge deck. Compared with a 3D heaving sectional model, distinct differences in sur...
Conference Paper
Full-text available
This paper describes the numerical modelling of air-water dual-bubble systems in which two initially spherical bubbles are allowed to rise, move around each other and possibly coalesce. The numerical model uses Computational Fluid Dynamics (CFD) and will eventually be validated against experiments, which are progressing in parallel. Here, we descri...
Conference Paper
This paper presents a numerical method based on a LES approach to modelling the unsteady flow around and the vortex-induced vibration (VIV) of a 5:1 rectangular cylinder in the smooth and turbulent flow. A fluid-structure interaction algorithm was also developed to model the aerodynamic behaviour of a half of the bridge deck in the bending and tors...
Conference Paper
Oil-air separation is a key function in aero engines with closed-loop oil systems. Typically, aero engine air/oil separators employ the use of a porous medium such as open cell metal foams, as a secondary separation mechanism. Assessing its impact on overall separation is important since non-captured oil is released overboard. Computational fluid d...
Article
Full-text available
In this work the practical applicability of a 2D URANS approach adopting a block structured mesh and Menter's SST k-ω turbulence model in fluid-structure interaction (FSI) problems is studied using as a test case a ratio B/H = 4 rectangular cylinder. The vortex-induced vibration (VIV) and torsional flutter phenomena are analyzed based on the comput...
Article
Increasing the efficiency in the process to numerically compute the flutter derivatives of bridge deck sections is desirable to advance the application of CFD based aerodynamic design in industrial projects. In this article, a 2D unsteady Reynolds-averaged Navier-Stokes (URANS) approach adopting Menter׳s SST k-ω turbulence model is employed for com...
Conference Paper
Full-text available
The k-turbulence model is routinely used by wind engineers to computationally model the Atmospheric Boundary-Layer (ABL). Commercial software is typically used, with the default law of the wall used to model the rough ground surface. By setting appropriate profiles for wind velocity and the turbulence quantities at the inlet, it is often assumed th...
Conference Paper
Full-text available
In this work the authors have studied the applicability of the 2D URANS approach adopting a block structured mesh and Menter’s SST k-omega turbulence model for the aspect ratio 4 rectangular cylinder. As a first step, a verification study is carried out for the mesh refinement level and the time step size. Then, the static response for a 0º angle o...
Conference Paper
In aero engines, the oil and air interaction within bearing chambers creates a complex two-phase flow. Since most aero engines use a close-loop oil system and releasing oil out is not acceptable, oil-air separation is essential. The oil originates from the engine transmission, the majority of which is scavenged out from the oil pump. The remainder...
Conference Paper
Full-text available
In this study the atmospheric flow field over a number of circular depressions with a sinusoidal profile and of various depths is resolved through the use of a Reynolds-Averaged Navier-Stokes (RANS) computational fluid dynamics (CFD) model. The effects of varying depression depth are examined in conjunction with variations in the atmospheric stabil...
Conference Paper
The computation of flutter derivatives of bridge decks is a challenging task since in some cases it is difficult to get an accurate match with available experimental data and it is also a burdensome problem from a computational perspective. Decreasing the number of required simulations for computing flutter derivatives while keeping a good accuracy...
Article
Full-text available
This paper examines the use of a coupled Computational Fluid Dynamics (CFD) – Rigid Body Dynamics (RBD) model to study the fixed-axis autorotation of a square flat plate. The calibration of the model against existing wind tunnel data is described. During the calibration, the CFD models were able to identify complex period autoration rates, which we...
Conference Paper
Full-text available
This paper aims to implement a strategy which incorporates wind variability into Computational Fluid Dynamics (CFD) models using the Moore (1976) formulation, thereby addressing the under-prediction of lateral plume spread in CFD models noted by Riddle et al. (2004). Here, a series of CFD simulations are run at various wind angles within a range of...
Conference Paper
Full-text available
This paper examines the use of a coupled Computational Fluid Dynamics (CFD)–Rigid Body Dynamics (RBD) model to study the fixed–axis autorotation of a flat plate. The model is compared against existing, experimentally-derived correlation functions that relate the mean tip speed ratio of the plate to aspect ratio, thickness ratio and mass moment of i...
Chapter
Computational fluid dynamics (CFD) has many applications in environmental flows but there are still challenges to be faced to increase its accuracy and ability to deal with more complex situations. At a fundamental level, CFD takes the physical laws of fluid flow and produces solutions in particular situations with the aid of computers. Whilst in g...
Article
Full-text available
The development of a coupled computational fluid-dynamics rigid body (CFD-RBD) model is presented. The RBD model deploys rotational quaternions, which are free from the gimbal lock that is associated with Euler rotational matrix. The quaternion model means that the complex 3D spinning flight modes associated with the flight of plate-type windborne...
Article
Full-text available
A coupled Computational Fluid Dynamics-Rigid Body Dynamics (CFD-RBD) model is presented, which is capable of modelling the 3D flight of plate-type windborne debris. The RBD model is based on rotational quaternions, which means that complex spinning modes of flight can be modelled accurately and robustly. For debris that is free to fly in the absenc...
Article
Full-text available
The application of computational fluid dynamics (CFD), particularly Large Eddy Simulation, for the modelling of buoyant turbulent plumes, has been demonstrated to be very accurate, but computationally expensive. Here a more basic, and therefore more generally practicable, approach is presented. Commercial CFD software is used to model such plumes u...
Conference Paper
This paper discusses two distinct issues that face modellers when using Computational Fluid Dynamics (CFD) to model the airborne dispersion of pollutants. Whether this be in open flat terrain or complex urban environments, the problem of specifying an appropriate turbulent Prandtl number is one which has been addressed by a number of researchers. T...
Article
Full-text available
There have existed for a number of years good practice guidelines for the use of Computational Fluid Dynamics (CFD) in the field of wind engineering. As part of those guidelines, details are given for the size of flow domain that should be used around a building of height, H. For low-rise buildings, the domain sizes produced by following the guidel...
Conference Paper
Full-text available
1 INTRODUCTION Windborne debris is one of the primary causes of building envelope failure and damage during severe storms. Plate type debris in particular presents a modelling challenge due to the complex non-linear Fluid-Structure Interaction (FSI) involved in its flight. Previously, a number of ana-lytical models have been presented to simulate t...
Article
This paper presents the use of computational fluid dynamics (CFD) to determine the distribution of the bed and sidewall shear stresses in trapezoidal channels. The impact of the variation of the slant angle of the side walls, aspect ratio, and composite roughness on the shear stress distribution is analyzed. The shear stress data can be directly ou...
Conference Paper
Full-text available
CityZoom is a computer-based tool where different design and planning attributes can be considered simultaneously, aiming to optimize the urban planning process. The current research has two objectives: (1) to enhance CityZoom and provide fast computation of air flow and pollution for urban planners; (2) to build an integrated CFD simulation into C...
Conference Paper
Full-text available
The phenomenon of plate autorotation is one that has application in a number of practical problems. Previous experimental investigations of autorotation have however been fo-cused on single degree of freedom autorotation about a fixed axis due to the practical difficulties involved with implementing full 3D autorotation. Numerical studies of the pr...
Conference Paper
The paper presents the application of a method for generating turbulent inflow for Large Eddy Simulations (LES) that was recently developed by Xie and Castro (2008). The method is based on inverse Fourier transforms, which are applied to prescribed spectra to pro-duce artificial turbulent inflows that respect given spatial and time correlations. Th...
Article
Increasingly in the process industries, the introduction of swirl flow upstream of bends is being used in particle-laden flow to reduce wear. This paper describes a computational fluid dynamics model of the swirl flow that is induced in an airflow passing through a horizontally mounted three-lobed helical pipe. It then goes on to discuss the result...
Article
The assumption of uniform flow permits the computation of the bed mean shear stress in open channels from the knowledge of the bed slope, hydraulic radius and fluid density alone. It is however important to distinguish between bank and bed shear values, in particular for sediment transport applications and research on this issue has been ongoing si...
Article
Full-text available
This paper describes the use of coupled Computational Fluid Dynamics (CFD) and Rigid Body Dynamics (RBD) in modelling the aerodynamic behaviour of wind-borne plate type objects. Unsteady 2D and 3D Reynolds Averaged Navier-Stokes (RANS) CFD models are used to simulate the unsteady and non-uniform flow field surrounding static, forced rotating, auto-...
Article
This study examines the hydrodynamic behaviour of rowing oar blades using computational fluid dynamics (CFD). For initial validation of the modelling technique, the lift and drag coefficients of the Big Blade oar design and a flat rectangular oar were compared against previously published experimental data carried out on quarter-scale blades held s...
Article
This paper examines the wind induced forces and moments experienced by a high sided lorry. Full-scale measurements are combined with wind tunnel and CFD simulations in order to gain an insight into the flow field around the vehicle. Differences and similarities between the three techniques are noted. It is shown that the rolling moment coefficient...
Article
The extraction of minerals from surface mines and quarries can produce significant fugitive dust emissions as a result of site activities such as blasting, road haulage, loading, crushing and stockpiling. If uncontrolled, these emissions can present serious environmental, health, safety and operational issues impacting both site personnel and the w...
Conference Paper
Full-text available
Urban areas are vulnerable to damage caused by wind borne debris generated from the failure of large items of street furniture, trees and unsecured items on the ground. The significance of impact loading due to debris has been recognised by the wind engineering community, Holmes [1], but current models of debris flight are limited and need to be im...
Article
Full-text available
This paper presents work on CFD simulations for sheet type wind borne debris. Although analytical models of debris flight exist, these models do not fully account for the unsteady flow fields around the sheets which influence the body forces acting on and the aero-elastic properties of the debris. 2D and 3D CFD models have been setup to investigate...
Article
Full-text available
In recent years much research has been carried out into the numerical simulation of wind loads on structures and in coupling CFD to dynamic models of structural response. In this paper the authors will present a study on simulating the dynamic response of a tall building to wind excitation Three sub problems are usually distinguished when solving f...
Article
The extraction and processing of minerals from surface mines and quarries can produce significant fugitive emissions as a result of site activities such as blasting, unpaved road haulage, loading, primary crushing and stockpiling. Uncontrolled fugitive dust emissions can present serious environmental, health, safety and operational issues impacting...