Publications
209 results found
Maddison JR, Marshall DP, Pain CC, et al., 2011, Accurate representation of geostrophic and hydrostatic balance in unstructured mesh finite element ocean modelling, OCEAN MODELLING, Vol: 39, Pages: 248-261, ISSN: 1463-5003
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- Citations: 11
Milthaler F, Xiang J, Pavlidis D, et al., 2011, The immersed body method combined with mesh adaptivity for solid-fluid coupling, 6th International Conference on Coastal Structures
Mitchell AJ, Allison PA, Gorman GJ, et al., 2011, Tidal circulation in an ancient epicontinental sea: The Early Jurassic Laurasian Seaway, Geology, Vol: 39, Pages: 207-210, ISSN: 0091-7613
Fang F, Pain CC, Navon IM, et al., 2011, The independent set perturbation adjoint method: A new method of differentiating mesh-based fluids models, International Journal for Numerical Methods in Fluids, Vol: In review
Farrell PE, Piggott MD, Gorman GJ, et al., 2011, Automated continuous verification for numerical simulation, Geoscientific Model Development, Vol: 4, Pages: 435-449
Munday DR, Marshall DP, Piggott MD, 2010, Idealised flow past an island in a dynamically adaptive finite element model, OCEAN DYNAMICS, Vol: 60, Pages: 835-850, ISSN: 1616-7341
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- Citations: 6
Southern J, Gorman GJ, Piggott MD, et al., 2010, Simulating cardiac electrophysiology using anisotropic mesh adaptivity, Journal of Computational Science, Vol: 1, Pages: 82-88
The simulation of cardiac electrophysiology requires small time steps and a fine mesh in order to resolve very sharp, but highly localized, wavefronts. The use of very high resolution meshes containing large numbers of nodes results in a high computational cost, both in terms of CPU hours and memory footprint. In this paper an anisotropic mesh adaptivity technique is implemented in the Chaste physiological simulation library in order to reduce the mesh resolution away from the depolarization front. Adapting the mesh results in a reduction in the number of degrees of freedom of the system to be solved by an order of magnitude during propagation and 2–3 orders of magnitude in the subsequent plateau phase. As a result, a computational speedup by a factor of between 5 and 12 has been obtained with no loss of accuracy, both in a slab-like geometry and for a realistic heart mesh with a spatial resolution of 0.125 mm.
Wells MR, Allison PA, Piggott MD, et al., 2010, Tidal modeling of an ancient tide-dominated seaway, part 1: model validation and application to global early Cretaceous (Aptian) tides, Journal of Sedimentary Research, Vol: 80, Pages: 393-410, ISSN: 1527-1404
Wells MR, Allison PA, Piggott MD, et al., 2010, Tidal modeling of an ancient tide-dominated seaway, part 2: the Aptian Lower Greensand seaway of northwest Europe, Journal of Sedimentary Research, Vol: 80, Pages: 411-439, ISSN: 1527-1404
Weller H, Ringler T, Piggott M, et al., 2010, CHALLENGES FACING ADAPTIVE MESH MODELING OF THE ATMOSPHERE AND OCEAN, BULLETIN OF THE AMERICAN METEOROLOGICAL SOCIETY, Vol: 91, Pages: 105-+, ISSN: 0003-0007
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- Citations: 21
Southern J, Gorman GJ, Piggott MD, et al., 2010, Anisotropic mesh adaptivity for cardiac electrophysiology, Pages: 929-938-929-938
Farrell PE, Piggott MD, Gorman GJ, et al., 2010, Automated continuous verification and validation for numerical simulation, Geoscientific Model Development Discussions, Vol: 3, Pages: 1587-1623
Garcia X, Pavlidis D, Gorman GJ, et al., 2010, A two-phase adaptive finite element method for solid–fluidcoupling in complex geometries, International Journal for Numerical Methods in Fluids
In this paper we present a method to solve the Navier–Stokes equations in complex geometries, suchas porous sands, using a finite-element solver but without the complexity of meshing the porous space.The method is based on treating the solid boundaries as a second fluid and solving a set of equationssimilar to those used for multi-fluid flow. When combined with anisotropic mesh adaptivity, it is possibleto resolve complex geometries starting with an arbitrary coarse mesh. The approach is validated bycomparing simulation results with available data in three test cases. In the first we simulate the flow pasta cylinder. The second test case compares the pressure drop in flow through random packs of sphereswith the Ergun equation. In the last case simulation results are compared with experimental data on theflow past a simplified vehicle model (Ahmed body) at high Reynolds number using large-eddy simulation(LES). Results are in good agreement with all three reference models.
Mitchell AJ, Allison PA, Piggott MD, et al., 2010, Numerical modelling of tsunami propagation with implications for sedimentation in ancient epicontinental seas: the Lower Jurassic Laurasian Seaway, Journal of Sedimentary Geology, Vol: 228, Pages: 81-97, ISSN: 0037-0738
Mitchell AJ, Ulicny D, Hampson GJ, et al., 2010, Modelling tidal current-induced bed shear stress and palaeocirculation in an epicontinental seaway: the Bohemian Cretaceous Basin, Central Europe, Sedimentology, Vol: 57, Pages: 359-388, ISSN: 0037-0746
Piggott MD, Farrell PE, Wilson CR, et al., 2009, Anisotropic mesh adaptivity for multi-scale ocean modelling, PHILOSOPHICAL TRANSACTIONS OF THE ROYAL SOCIETY A-MATHEMATICAL PHYSICAL AND ENGINEERING SCIENCES, Vol: 367, Pages: 4591-4611, ISSN: 1364-503X
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- Citations: 63
Fang F, Pain CC, Navon IM, et al., 2009, A POD goal-oriented error measure for mesh optimization, International Journal for Numerical Methods in Fluids, Vol: 63, Pages: 185-206, ISSN: 1097-0363
The approach for designing an error measure to guide an adaptive meshing algorithm proposed in Power et al. (Ocean Modell. 2006; 15:3-38) is extended to use a POD adjoint-based method, thus facilitating efficient primal and adjoint integration in time. The aim is to obtain a new mesh that can adequately resolve all the fields at all time levels, with optimal (w.r.t. the functional) efficiency. The goal-based method solves both the primal and adjoint equations to form the overall error norms, in the form of a metric tensor. The tetrahedral elements are then optimized so that they have unit size in Riemannian space defined with respect to the metric tensor.This is the first attempt to use POD to estimate an anisotropic error measure. The metric tensor field can be used to direct anisotropic mesh adaptivity. The resulting mesh is optimized to efficiently represent the solution fields over a given time period. The calculation of the error measures is carried out in the reduced space. The POD approach facilitates efficient integration backwards in time and yields the sensitivity analysis necessary for the goal-based error estimates. The accuracy of both the primal and adjoint-reduced models is thus optimized (through the use of anisotropic mesh adaptivity). In addition, the functional for optimizing meshes has been designed to be consistent with that for 4D Var data assimilation.
Fang F, Pain CC, Navon IM, et al., 2009, Reduced-order modelling of an adaptive mesh ocean model, INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN FLUIDS, Vol: 59, Pages: 827-851
Slingo J, Bates K, Nikiforakis N, et al., 2009, Developing the next-generation climate system models: challenges and achievements, PHILOSOPHICAL TRANSACTIONS OF THE ROYAL SOCIETY A-MATHEMATICAL PHYSICAL AND ENGINEERING SCIENCES, Vol: 367, Pages: 815-831, ISSN: 1364-503X
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- Citations: 46
Ham DA, Farrell PE, Gorman GJ, et al., 2009, Spud 1.0: generalising and automating the user interfaces of scientific computer models, Geoscientific Model Development, Vol: 2, Pages: 33-42
The interfaces by which users specify the scenarios to be simulated by scientific computer models are frequently primitive, under-documented and ad-hoc text files which make using the model in question difficult and error-prone and significantly increase the development cost of the model. In this paper, we present a model-independent system, Spud, which formalises the specification of model input formats in terms of formal grammars. This is combined with an automated graphical user interface which guides users to create valid model inputs based on the grammar provided, and a generic options reading module, libspud, which minimises the development cost of adding model options. Together, this provides a user friendly, well documented, self validating user interface which is applicable to a wide range of scientific models and which minimises the developer input required to maintain and extend the model interface.
Latham JP, Mindel J, Xiang J, et al., 2009, Coupled FEMDEM/Fluids for coastal engineers with special reference to armour stability and breakage, Geomechanics and Geoengineering, Vol: 4, Pages: 39-53, ISSN: 1748-6033
Gorman GJ, Pain CC, Piggott MD, et al., 2009, Interleaved parallel tetrahedral mesh optimisation and dynamic load-balancing, Brussels, Belgium, the fourth International Conference on Adaptive Modeling and Simulation
Fang F, Pain CC, Navon IM, et al., 2009, A POD reduced-order 4D-Var adaptive mesh ocean modelling approach, Int. J. Numer. Meth. Fluids, Vol: 60, Pages: 709-732
This paper presents a novel approach for inverting a complex ocean model via a proper orthogonal decomposition. The inversion is achieved through the construction of an adjoint model and used to assimilate data in a similar manner to that used in weather forecasting. This is an incredibly important capability for an ocean model, however it is both complex to construct and also can be computationally expensive. The approach proposed here addresses both of these important issues by constructing an efficient and easy to compute adjoint directly from the reduced order model. The approach is demonstrated by inverting for initial conditions in an ocean gyre simulation. The methodology proposed here led directly to the award of a £1M EPSRC grant (EP/I00405X) to develop reduced order and adjoint models for coastal oceanography. Cited 11 times.
Ham DA, Farrell PE, Gorman GJ, et al., 2009, Spud 1.0: generalising and automating the user interfaces of scientific computer models, GEOSCIENTIFIC MODEL DEVELOPMENT, Vol: 2, Pages: 33-42, ISSN: 1991-959X
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- Citations: 10
Fang F, Pain CC, Navon IM, et al., 2009, A POD reduced order unstructured mesh ocean modelling method for moderate Reynolds number flows, Ocean Modelling, Vol: 28, Pages: 127-136, ISSN: 1463-5003
Farrell PE, Piggott MD, Pain CC, et al., 2009, Conservative interpolation between unstructured meshes via supermesh construction, Computer Methods in Applied Mechanics and Engineering, Vol: 198, Pages: 2632-2642
Gorman GJ, Piggott MD, Wells MR, et al., 2008, A systematic approach to unstructured mesh generation for ocean modelling using GMT and Terreno, Computers & Geosciences, Vol: 34, Pages: 1721-1731, ISSN: 0098-3004
A systematic approach to unstructured mesh generation for ocean modelling is presented. The method optimises unstructured meshes to approximate bathymetry to a user specified accuracy which may be defined as a function of longitude, latitude and bathymetry. GMT (Generic Mapping Tools) is used to perform the initial griding of the bathymetric data. Subsequently, the Terreno meshing package combines automated shoreline approximation, mesh gradation and optimisation methods to generate high-quality bathymetric meshes. The operation of Terreno is based upon clearly defined error measures and this facilitates the automation of unstructured mesh generation while minimising user intervention and the subjectivity that this can introduce.
Latham J-P, Munjiza A, Mindel J, et al., 2008, Modelling of massive particulates for breakwater engineering using coupled FEMDEM and CFD, PARTICUOLOGY, Vol: 6, Pages: 572-583, ISSN: 1674-2001
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- Citations: 33
Wells MR, Allison PA, Hampson GJ, et al., 2008, Investigating tides in the Early Pennsylvanian Seaway of NW Eurasia using the Imperial College Ocean Model, Geological Association of Canada Special Paper, Vol: 48, Pages: 363-387, ISSN: 0072-1042
Piggott MD, Gorman GJ, Pain CC, et al., 2008, A new computational framework for multi-scale ocean modelling based on adapting unstructured meshes, 9th ICFD Conference on Numerical Methods for Fluid Dynamics, Pages: 1003-1015
A new modelling framework is presented for application to a range of three-dimensional (3D) multi-scale oceanographic problems. The approach is based upon a finite element discretization on an unstructured tetrahedral mesh which is optimized to represent highly complex geometries. Throughout a simulation the mesh is dynamically adapted in 3D to optimize the representation of evolving solution structures. The adaptive algorithm makes use of anisotropic measures of solution complexity and a load-balanced parallel mesh optimization algorithm to vary resolution and allow long, thin elements to align with features such as boundary layers. The modelling framework presented is quite different from the majority of ocean models in use today, which are typically based on static-structured grids. Finite element (and volume) methods on unstructured meshes are, however, gaining popularity in the oceanographic community. The model presented here is novel in its use of unstructured meshes and anisotropic adaptivity in 3D, its ability to represent a range of coupled multi-scale solution structures and to simulate non-hydrostatic dynamics. Copyright (C) 2007 John Wiley & Sons, Ltd.
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