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  • Conference paper
    Vire A, Xiang J, Piggott M, Cotter C, Pain Cet al., 2013,

    Towards the fully-coupled numerical modelling of floating wind turbines

    , 10th Deep Sea Offshore Wind R and D Conference (DeepWind), Publisher: ELSEVIER SCIENCE BV, Pages: 43-51, ISSN: 1876-6102
  • Journal article
    Jacobs CT, Collins GS, Piggott MD, Kramer SC, Wilson CRGet al., 2013,

    Multiphase flow modelling of volcanic ash particle settling in water using adaptive unstructured meshes

    , Geophysical Journal International, Vol: 192, Pages: 647-665

    Small-scale experiments of volcanic ash particle settling in water have demonstrated that ash particles can either settle slowly and individually, or rapidly and collectively as a gravitationally unstable ash-laden plume. This has important implications for the emplacement of tephra deposits on the seabed. Numerical modelling has the potential to extend the results of laboratory experiments to larger scales and explore the conditions under which plumes may form and persist, but many existing models are computationally restricted by the fixed mesh approaches that they employ. In contrast, this paper presents a new multiphase flow model that uses an adaptive unstructured mesh approach. As a simulation progresses, the mesh is optimized to focus numerical resolution in areas important to the dynamics and decrease it where it is not needed, thereby potentially reducing computational requirements. Model verification is performed using the method of manufactured solutions, which shows the correct solution convergence rates. Model validation and application considers 2-D simulations of plume formation in a water tank which replicate published laboratory experiments. The numerically predicted settling velocities for both individual particles and plumes, as well as instability behaviour, agree well with experimental data and observations. Plume settling is clearly hindered by the presence of a salinity gradient, and its influence must therefore be taken into account when considering particles in bodies of saline water. Furthermore, individual particles settle in the laminar flow regime while plume settling is shown (by plume Reynolds numbers greater than unity) to be in the turbulent flow regime, which has a significant impact on entrainment and settling rates. Mesh adaptivity maintains solution accuracy while providing a substantial reduction in computational requirements when compared to the same simulation performed using a fixed mesh, highlighting the benefits of an adapt

  • Journal article
    Hassan MHA, Johnson HD, Allison PA, Abdullah WHet al., 2013,

    Sedimentology and stratigraphic development of the upper Nyalu Formation (Early Miocence), Sarawak, Malaysia: A mixed wave and tide influenced coastal system

    , Journal of Asian Earth Sciences
  • Conference paper
    Lange M, Gorman G, Weiland M, Mitchell L, Southern Jet al., 2013,

    Acieving efficient strong scaling with PETSc using hybrid MPI/OpenMP optimisations

    , Publisher: Springer Berlin Heidelberg, Pages: 97-108
  • Conference paper
    Markall GR, Rathgeber F, Mitchell L, Loriant N, Bertolli C, Kelly PHJ, Markall G, Rathgeber F, Ham D, Loriant N, Mitchell L, Bertolli C, Kelly Pet al., 2013,

    Performance-Portable Finite Element Assembly Using PyOP2 and FEniCS

    , International Supercomputing Conference (ISC), Publisher: Springer, Pages: 279-289, ISSN: 0302-9743

    We describe a toolchain that provides a fully automated compilation pathway from a finite element domain-specific language to low-level code for multicore and GPGPU platforms. We demonstrate that the generated code exceeds the performance of the best available alternatives, without requiring manual tuning or modification of the generated code. The toolchain can easily be integrated with existing finite element solvers, providing a means to add performance portable methods without having to rebuild an entire complex implementation from scratch.

  • Journal article
    Potter RWK, Collins GS, 2013,

    Numerical modeling of asteroid survivability and possible scenarios for the Morokweng crater-forming impact

    , Meteoritics & Planetary Science, Vol: 48, Pages: 744-757, ISSN: 1945-5100
  • Journal article
    Potter RWK, Kring DA, Collins GS, Kiefer WS, McGovern PJet al., 2013,

    Numerical modeling of the formation and structure of the Orientale impact basin

    , Journal of Geophysical Research: Planets, Pages: n/a-n/a, ISSN: 2169-9100
  • Journal article
    Brito-Parada PR, Neethling SJ, Cilliers JJ, 2013,

    Modelling the behaviour of the wetting front in non-standard forced foam drainage scenarios

    , Colloids and Surfaces A: Physicochemical and Engineering Aspects
  • Journal article
    Goffin MA, Baker CMJ, Buchan AG, Pain CC, Eaton MD, Smith PNet al., 2013,

    Minimising the error in eigenvalue calculations involving the Boltzmann transport equation using goal-based adaptivity on unstructured meshes

    , Journal of Computational Physics, Vol: 242, Pages: 726-762

    This article presents a method for goal-based anisotropic adaptive methods for the finite element method applied to the Boltzmann transport equation. The neutron multiplication factor, keff, is used as the goal of the adaptive procedure. The anisotropic adaptive algorithm requires error measures for keff with directional dependence. General error estimators are derived for any given functional of the flux and applied to keff to acquire the driving force for the adaptive procedure. The error estimators require the solution of an appropriately formed dual equation. Forward and dual error indicators are calculated by weighting the Hessian of each solution with the dual and forward residual respectively. The Hessian is used as an approximation of the interpolation error in the solution which gives rise to the directional dependence. The two indicators are combined to form a single error metric that is used to adapt the finite element mesh. The residual is approximated using a novel technique arising from the sub-grid scale finite element discretisation. Two adaptive routes are demonstrated: (i) a single mesh is used to solve all energy groups, and (ii) a different mesh is used to solve each energy group. The second method aims to capture the benefit from representing the flux from each energy group on a specifically optimised mesh. The keff goal-based adaptive method was applied to three examples which illustrate the superior accuracy in criticality problems that can be obtained.

  • Conference paper
    Jordan N, Allison PA, Hill JH, Sutton MDet al., 2012,

    Carbonates, ammonites and the fate of aragonite: a new perspective from the Lower Jurassic of Lyme Regis

    , British Sedimentological Research Group Annual Meeting

    The Lower Jurassic Blue Lias Formation at Lyme Regis, Dorset, preserves a diverse assemblage of invertebrate and vertebrate fossils within rhythmic packages of shales, marls and carbonates. One limestone bed in particular, Bed 29, preserves a unique pavement of very large (up to 72 cm) ammonites, initially buried in carbonate mud before diagenetic cementation. The ammonite accumulation is most likely due to sedimentological condensation but the mechanisms for preserving an aragonitic shell long enough for it to be neomorphosed to calcite on the seabed are a challenge for conventional taphonomic models. It has been suggested that early dissolution of aragonite is a major process in offshore deeper ramp settings, resulting in the removal of sediment prior to lithification. We present field-based evidence for a new model of aragonite preservation within a cyclic oxic-anoxic carbonate environment, using ammonite preservation to track the fate of aragonite in different depositional environments. The carbonate sediment provides a short-term geochemical buffer that militates against the dissolution of aragonite sediment and molluscs, allowing neomorphism to calcite under some conditions. The broader implications of this model for the preservation of molluscan shells and reduced sediment dissolution in carbonate environments under variably oxygenated conditions are evaluated.

  • Conference paper
    Barker DJ, Neethling SJ, Parameswaran G, 2012,

    SPH Simulation of Packed-beds and ColumnsApplied to Heap-leaching

    , CFD 2012
  • Journal article
    Hossen MJ, Navon IM, Fang F, 2012,

    A penalized four-dimensional variational data assimilation method for reducing forecast error related to adaptive observations

  • Journal article
    Milthaler FFM, Gorman GJ, Piggott MD, 2012,

    Reducing spurious drag forces when using mesh adaptivity in CFD

    , ECCOMAS 2012 - European Congress on Computational Methods in Applied Sciences and Engineering, e-Book Full Papers, Pages: 5621-5640

    This work explores the impact of mesh adaptivity methods in combination with fixed as well as adaptive timestepping when modelling fluid dynamical systems that are sensitive to minor changes in the fluid's pressure and velocity. Here the diagnostic of interest for fluidsolid interaction modelling is the drag force. Depending on the solid's properties, even minor unphysical abrupt changes, so-called peaks, in the drag force - due to mesh adaptivity - could lead to a major disturbance in the model. For such systems the need naturally arises to reduce these peaks to a certain degree, until the sudden changes are small enough to be neglected. Hence, in this paper a variety of approaches are described and compared against one another, that aim to reduce these peaks. Moreover, further studies show the relation between the peaks in the drag force to the timestep, and pressure. The 3D-CFD software Fluidity, which uses an arbitrarily unstructured mesh, and a 3D mesh optimization algorithm was used for this case-study.

  • Journal article
    Viré A, Xiang J, Milthaler F, Farrell P, Piggott MD, Latham JP, Pavlidis D, Pain CCet al., 2012,

    Modelling of fluid–solid interactions using an adaptive mesh fluid model coupled with a combined finite–discrete element model

    , Ocean Dynamics
  • Journal article
    Buchan AG, Pain CC, Umpleby AP, Smedley-Stevenson RPet al., 2012,

    A sub-grid scale finite element agglomeration multigrid method with application to the Boltzmann transport equation

  • Journal article
    Morris G, Neethling SJ, Cilliers JJ, 2012,

    Identifying the Transition Capillary Pressure of a Superhydrophobic Surface Containing Cylindrical Rods

    , CHEMISTRY LETTERS, Vol: 41, Pages: 1303-1305, ISSN: 0366-7022
  • Journal article
    Neethling SJ, Cilliers JJ, 2012,

    Grade-recovery curves: A new approach for analysis of and predicting from plant data

    , MINERALS ENGINEERING, Vol: 36-38, Pages: 105-110, ISSN: 0892-6875
  • Journal article
    Buchan A, Eaton MD, Goddard AJH, Pain CCet al., 2012,

    Simulated transient dynamics and heat transfer characteristics of the water boiler nuclear reactor SUPO with cooling coil heat extraction

    , Annals of nuclear energy, Vol: 48, Pages: 68-83

    The term “water boiler” reactor refers to a type of aqueous homogeneous reactor (AHR) that was designed, built and operated by Los Alamos in the 1940s. This was the first type of liquid fuelled reactor and the first to be fuelled with enriched Uranium. For security reasons the term “water boiler” was adopted and three versions were built: LOPO (for low power), HYPO (for high power) and SUPO (for super power) which were spherical shaped reactor vessels. The name was appropriate as the reactors appeared to boil although this was actually due to the release of radiolytic gas bubbles; although SUPO was operated during some studies close to the boiling point of uranyl nitrate. The final water boiler “SUPO” was operated almost daily as a neutron source from 1951 until its deactivation in 1974-23 years of safe, reliable operation. Many of the key neutron measurements needed in the design of the early atomic weapons were made using LOPO, HYPO and SUPO. More recently SUPO has been considered as a benchmark for quasi-steady-state operation of AHRs with internal cooling structures.This paper presents modelling and analysis of the coupled neutronic and fluid time dependent characteristics of the SUPO reactor. In particular the quasi-steady-state dynamics of SUPO have been investigated together with its heat transfer characteristics. In the simulations presented the SUPO reactor is modelled using the spatially dependent neutron/multiphase CFD simulation tool, FETCH, at a quasi-steady-state power of 25 kW. SUPO also possessed a cooling coil system that fed cooling water through the reactor for the extraction of the fission and decay heat. This cooling system, and the heat extraction, is modelled in the simulations using a new sub-modelling approach that is detailed here. The results from this simulation, such as gas fraction, gas generation rate, coolant rate and average temperature, are compared against the available experimental information.

  • Journal article
    Potter RWK, Kring DA, Collins GS, Kiefer WS, McGovern PJet al., 2012,

    Estimating transient crater size using the crustal annular bulge: Insights from numerical modeling of lunar basin-scale impacts

  • Journal article
    Solano JMS, Jackson MD, Sparks RSJ, Blundy JD, Annen Cet al., 2012,

    Melt Segregation in Deep Crustal Hot Zones: a Mechanism for Chemical Differentiation, Crustal Assimilation and the Formation of Evolved Magmas

    , Journal of Petrology, Vol: 53, Pages: 1999-2026, ISSN: 1460-2415

    Mantle-derived basaltic sills emplaced in the lower crust provide amechanism for the generation of evolved magmas in deep crustal hotzones (DCHZ).This study uses numerical modelling to characterizethe time required for evolved magma formation, the depth and temperatureat which magma formation occurs, and the composition ofthe magma.The lower crust is assumed to comprise amphibolite. Inan extension of previous DCHZ models, the new model couples heattransfer during the repetitive emplacement of sills with mass transfervia buoyancy-driven melt segregation along grain boundaries.The resultsshed light on the dynamics of DCHZ development and evolution.TheDCHZ comprises a mush of crystals plus interstitial melt,except when a new influx of basaltic magma yields a short-lived(20^200 years) reservoir of melt plus suspended crystals (magma).Melt segregation and accumulation within the mush yields two contrastingmodes of evolved magma formation, which operate over timescalesof c. 10 kyr-1 Myr, depending upon emplacement rate andstyle. In one, favoured by emplacement via over-accretion, or emplacementat high rates, evolved magma forms in the crust overlying theintruded basalt sills, and is composed of crustal partial melt, and residualmelt that has migrated upwards out of the crystallizingbasalt. In the other, favoured by emplacement via under- orintra-accretion, or by emplacement at lower rates, evolved magmaforms in the intruded basalt, and the resulting magma is composedprimarily of residual melt. In all cases, the upward migration ofbuoyant melt yields cooler and more evolved magmas, which arebroadly granitic in composition. Chemical differentiation is thereforedriven by melt migration, because the melt migrates through, andchemically equilibrates with, partially molten rock at progressivelylower temperatures. Crustal assimilation occurs during partial melting,and mixing of crustal and residual melt occurs when residualmelt migrates into the partially molten crust, yielding

  • Journal article
    Sakai M, Takahashi H, Pain CC, Latham J-P, Xiang Jet al., 2012,

    Study on a large-scale discrete element model for fine particles in a fluidized bed

    , ADVANCED POWDER TECHNOLOGY, Vol: 23, Pages: 673-681, ISSN: 0921-8831
  • Journal article
    Ilankoon IMSK, Neethling SJ, 2012,

    Hysteresis in unsaturated flow in packed beds and heaps

    , MINERALS ENGINEERING, Vol: 35, Pages: 1-8, ISSN: 0892-6875
  • Journal article
    Baker CMJ, Buchan AG, Pain CC, Tollit B, Eaton MD, Warner Pet al., 2012,

    Quadratic inner element subgrid scale discretisation of the Boltzmann transport equation

    , Annals of Nuclear Energy, Vol: 45, Pages: 124-137

    This paper explores the application of the inner element subgrid scale method to the Boltzmann transport equation using quadratic basis functions. Previously, only linear basis functions for both the coarse scale and the fine scale were considered. This paper, therefore, analyses the advantages of using different coarse and subgrid basis functions for increasing the accuracy of the subgrid scale method. The transport of neutral particle radiation may be described by the Boltzmann transport equation (BTE) which, due to its 7 dimensional phase space, is computationally expensive to resolve. Multi-scale methods offer an approach to efficiently resolve the spatial dimensions of the BTE by separating the solution into its coarse and fine scales and formulating a solution whereby only the computationally efficient coarse scales need to be solved. In previous work an inner element subgrid scale method was developed that applied a linear continuous and discontinuous finite element method to represent the solution’s coarse and fine scale components. This approach was shown to generate efficient and stable solutions, and so this article continues its development by formulating higher order quadratic finite element expansions over the continuous and discontinuous scales. Here it is shown that a solution’s convergence can be improved significantly using higher order basis functions. Furthermore, by using linear finite elements to represent coarse scales in combination with quadratic fine scales, convergence can also be improved with only a modest increase in computational expense.

  • Journal article
    Elsheikh AH, Jackson MD, Laforce TC, 2012,

    Bayesian Reservoir History Matching Considering Model and Parameter Uncertainties

    , MATHEMATICAL GEOSCIENCES, Vol: 44, Pages: 515-543, ISSN: 1874-8961
  • Journal article
    Morris G, Neethling SJ, Cilliers JJ, 2012,

    Modelling the self orientation of particles in a film

    , MINERALS ENGINEERING, Vol: 33, Pages: 87-92, ISSN: 0892-6875
  • Conference paper
    Nygaard ET, Pain CC, Eaton MD, Gomes JLMA, Goddard AJH, Gorman GJ, Tollit B, Buchan AG, Cooling CM, Angelo PLet al., 2012,

    Steps Towards Verification and Validation of the FETCH Code for Level 2 Analysis, Design and Optimization of Aqueous Homogeneous Reactors

    , PHYSOR
  • Journal article
    Collins GS, 2012,

    Moonstruck magnetism

    , Science, Vol: 335, Pages: 1176-1177
  • Journal article
    Glover PWJ, Walker E, Jackson MD, 2012,

    Streaming-potential coefficient of reservoir rock: A theoretical model

    , Geophysics, Vol: 77, Pages: D17-D43, ISSN: 1942-2156

    The streaming potential is that electrical potential whichdevelops when an ionic fluid flows through the pores of a rock.It is an old concept that is recently being applied in many fieldsfrom monitoring water fronts in oil reservoirs to understandingthe mechanisms behind synthetic earthquakes. We have carriedout fundamental theoretical modeling of the streaming-potentialcoefficient as a function of pore fluid salinity, pH, and temperatureby modifying the HS equation for use with porous rocksand using input parameters from established fundamental theory(the Debye screening length, the Stern-plane potential, the zetapotential, and the surface conductance). The model also requiresthe density, electrical conductivity, relative electric permittivityand dynamic viscosity of the bulk fluid, for which empiricalmodels are used so that the temperature of the model may bevaried. These parameters are then combined with parametersthat describe the rock microstructure. The resulting theoreticalvalues have been compared with a compilation of data for siliceousmaterials comprising 290 streaming-potential coefficientmeasurements and 269 zeta-potential measurements obtainedexperimentally for 17 matrix-fluid combinations (e.g., sandstonesaturated with KCl), using data from 29 publications.The theoretical model was found to ably describe the main featuresof the data, whether taken together or on a sample by samplebasis. The low-salinity regime was found to be controlled bysurface conduction and rock microstructure, and was sensitiveto changes in porosity, cementation exponent, formation factor,grain size, pore size and pore throat size as well as specific surfaceconductivity. The high-salinity regime was found to be subjectto a zeta-potential offset that allows the streaming-potentialcoefficient to remain significant even as the saturation limit isapproached

  • Journal article
    Kramer SC, Wilson CR, Davies DR, 2012,

    An implicit free surface algorithm for geodynamical simulations

    , PHYSICS OF THE EARTH AND PLANETARY INTERIORS, Vol: 194, Pages: 25-37, ISSN: 0031-9201
  • Journal article
    Collins GS, Melosh HJ, Osinski GR, 2012,

    The Impact-Cratering Process

    , ELEMENTS, Vol: 8, Pages: 25-30, ISSN: 1811-5209
  • Journal article
    Jackson MD, Vinogradov J, 2012,

    Impact of wettability on laboratory measurements of streaming potential in carbonates

  • Journal article
    Latham JP, Xiang J, Belayneh M, Nick HM, Tsang C, Blunt MJet al., 2012,

    Modelling stress-dependent permeability in fractured rock including effects of propagating and bending fractures

    , International Journal of Rock Mechanics and Mining Sciences, Vol: 57, Pages: 100-112
  • Conference paper
    Rathgeber F, Markall GR, Mitchell L, Loriant N, Ham DA, Bertolli C, Kelly PHJ, Rathgeber F, Markall GR, Mitchell L, Loriant N, Ham DA, Bertolli C, Kelly PHJet al., 2012,

    PyOP2: A High-Level Framework for Performance-Portable Simulations on Unstructured Meshes

    , High Performance Computing, Networking Storage and Analysis, SC Companion, Publisher: IEEE Computer Society, Pages: 1116-1123

    Emerging many-core platforms are very difficult to program in a performance portable manner whilst achieving high efficiency on a diverse range of architectures. We present work in progress on PyOP2, a high-level embedded domain-specific language for mesh-based simulation codes that executes numerical kernels in parallel over unstructured meshes. Just-in-time kernel compilation and parallel scheduling are delayed until runtime, when problem-specific parameters are available. Using generative metaprogramming, performance portability is achieved, while details of the parallel implementation are abstracted from the programmer. PyOP2 kernels for finite element computations can be generated automatically from equations given in the domain-specific Unified Form Language. Interfacing to the multi-phase CFD code Fluidity through a very thin layer on top of PyOP2 yields a general purpose finite element solver with an input notation very close to mathematical formulae. Preliminary performance figures show speedups of up to 3.4x compared to Fluidity's built-in solvers when running in parallel.

  • Conference paper
    Lange M, Field T, 2012,

    Accelerating agent-based ecosystem models using the cell broadband engine

    , Berlin, Heidelberg, Publisher: Springer-Verlag, Pages: 1-12
  • Journal article
    Weiland M, Mitchell L, Gorman G, Kramer S, Southern J, Parsons Met al., 2012,

    Mixed-mode implementation of PETSc for scalable linear algebra on multi-core processors

  • Conference paper
    Gorman GJ, Southern J, Farrell PE, Piggott MD, Rokos G, Kelly PHJet al., 2012,

    Hybrid OpenMP/MPI anisotropic mesh smoothing

    , International Conference on Computational Science (ICCS), Publisher: ELSEVIER SCIENCE BV, Pages: 1513-1522, ISSN: 1877-0509
  • Conference paper
    Brito-Parada PR, Neethling SJ, Cilliers JJ, 2012,

    Forced drainage simulations in 2D and 3D foams

    , 9th European Conference on Foams and Emulsions
  • Journal article
    Brito-Parada PR, Neethling SJ, Cilliers JJ, 2012,

    CFD study of liquid drainage in flotation foams

    , Computer Aided Chemical Engineering
  • Journal article
    Potter RWK, Collins GS, Kiefer WS, McGovern PJ, Kring DAet al., 2012,

    Constraining the size of the South Pole-Aitken basin impact

    , Icarus, Vol: 220, Pages: 730 - 743-730 - 743, ISSN: 0019-1035
  • Journal article
    Davison TM, Ciesla FJ, Collins GS, 2012,

    Post-Impact Thermal Evolution of Porous Planetesimals

    , Geochimica et Cosmochimica Acta, Vol: 95, Pages: 252-269, ISSN: 0016-7037
  • Journal article
    Jackson MD, Leinov E, 2012,

    On the Validity of the “Thin” and “Thick”Double-Layer Assumptions When CalculatingStreaming Currents in Porous Media

    , International Journal of Geophysics, Vol: 2012, ISSN: 1687-8868

    We find that the thin double layer assumption, in which the thickness of the electrical diffuse layer is assumed small comparedto the radius of curvature of a pore or throat, is valid in a capillary tubes model so long as the capillary radius is >200 times thedouble layer thickness, while the thick double layer assumption, in which the diffuse layer is assumed to extend across the entirepore or throat, is valid so long as the capillary radius is >6 times smaller than the double layer thickness. At low surface chargedensity (<10 mC · m−2) or high electrolyte concentration (>0.5 M) the validity criteria are less stringent. Our results suggest thatthe thin double layer assumption is valid in sandstones at low specific surface charge (<10 mC · m−2), but may not be valid insandstones of moderate- to small pore-throat size at higher surface charge if the brine concentration is low (<0.001 M). The thickdouble layer assumption is likely to be valid in mudstones at low brine concentration (<0.1 M) and surface charge (<10 mC·m−2),but at higher surface charge, it is likely to be valid only at low brine concentration (<0.003 M). Consequently, neither assumptionmay be valid in mudstones saturated with natural brines.

  • Journal article
    Du J, Fang F, Pain CC, Navon IM, Zhu J, Ham DAet al., 2012,

    POD reduced-order unstructured mesh modelling applied to 2D and 3D fluid flow

    , Computers & Mathematics with Applications
  • Conference paper
    Brito-Parada PR, Neethling SJ, Cilliers JJ, 2012,

    CFD study of liquid drainage in flotation foams

    , 22nd European Symposium on Computer Aided Process Engineering (ESCAPE 22)
  • Journal article
    Cole KE, Brito-Parada PR, Xu C, Neethling SJ, Cilliers JJet al., 2012,

    Experimental studies and numerical model validation of overflowing 2D foam to test flotation cell crowder designs

    , Chemical Engineering Research and Design
  • Conference paper
    Miljkovic K, Collins GS, Chapman DJ, Patel MR, Proud WGet al., 2012,


    , 7th Biennial Conference of the American-Physical-Society-Topical-Group on Shock Compression of Condensed Matter, Publisher: AMER INST PHYSICS, ISSN: 0094-243X
  • Journal article
    Brito-Parada PR, Cilliers JJ, 2012,

    Experimental and numerical studies of launder configurations in a two-phase flotation system

    , Minerals Engineering
  • Journal article
    Jackson MD, Butler AP, Vinogradov J, 2012,

    Measurements of Spontaneous Potential in Chalk with Application to Aquifer Characterisation in the Southern UK

    , Quarterly Journal of Engineering Geology and Hydrogeology
  • Journal article
    Jackson MD, Gulamali MY, Leinov E, Saunders JH, Vinogradov Jet al., 2012,

    Spontaneous Potentials in Hydrocarbon Reservoirs during Waterflooding: Application to Waterfront Monitoring

    , SPE Journal
  • Journal article
    Bray VJ, Schenk PM, Melosh HJ, Morgan JV, Collins GSet al., 2012,

    Ganymede crater dimensions – Implications for central peak and central pit formation and development

    , Icarus, Vol: 217, Pages: 115-129

    The morphology of impact craters on the icy Galilean satellites differs from craters on rocky bodies. Thedifferences are thought due to the relative weakness of ice and the possible presence of sub-surface waterlayers. Digital elevation models constructed from Galileo images were used to measure a range of dimensionsof craters on the dark and bright terrains of Ganymede. Measurements were made from multipleprofiles across each crater, so that natural variation in crater dimensions could be assessed and averagedscaling trends constructed. The additional depth, slope and volume information reported in this work hasenabled study of central peak formation and development, and allowed a quantitative assessment of thevarious theories for central pit formation. We note a possible difference in the size-morphology progressionbetween small craters on icy and silicate bodies, where central peaks occur in small craters beforethere is any slumping of the crater rim, which is the opposite to the observed sequence on the Moon. Conversely,our crater dimension analyses suggest that the size-morphology progression of large lunar cratersfrom central peak to peak-ring is mirrored on Ganymede, but that the peak-ring is subsequentlymodified to a central pit morphology. Pit formation may occur via the collapse of surface material intoa void left by the gradual release of impact-induced volatiles or the drainage of impact melt intosub-crater fractures.

  • Journal article
    Brito-Parada PR, Kramer SC, Wilson CR, Pain CC, Neethling SJ, Cilliers JJet al., 2012,

    A finite element formulation to model the flow of flotation foams

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