Publications
129 results found
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
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 unstructured mesh ocean modelling method for moderate Reynolds number flows Ocean Modelling, Ocean Modelling, Vol: 28, Pages: 127-136
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
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
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.
Ham D, Farrell P, Gorman G, et al., 2008, Spud
Spud is a generic system for defining, writing and processing options files for scientific computer models.The interfaces to scientific computer models are frequently primitive, under-documented and ad-hoc text files. This makes using and developing the model in question difficult and error-prone.With Spud, the model developer need only write a rules file (schema) which defines the options which the model takes and the relationship between them. The Spud component Diamond then provides an automatically generated graphical user interface which guides the user and validates the user's input against the schema. Diamond writes out an xml options file for use in Spud.The developer then uses libspud to read the options file into the model. Libspud can read any valid options file without further code modifications and makes the options available at any point in the model code at which they are required.Spud further provides the facility for the schema to be self-documenting and Diamond presents this documentation to the model user in a context-sensitive manner.
Piggott MD, Gorman GJ, Pain CC, et al., 2008, A new computational framework for multi-scale ocean modelling based on adapting unstructured meshes, International Journal for Numerical Methods in Fluids, Vol: 56, Pages: 1003-1015
Shaw B, Ambraseys NN, England PC, et al., 2008, Eastern Mediterranean tectonics and tsunami hazard inferred from the : AD: 365 earthquake, Nature Geoscience
Shaw B, Ambraseys NN, England PC, et al., 2008, Eastern Mediterranean tectonics and tsunami hazard inferred from the AD 365 earthquake, Nature Geoscience, Vol: 1, Pages: 268-276
C J Cotter, G Gorman, 2008, Diagnostic tools for 3D unstructured oceanographic data, Ocean Modelling, Vol: 20, Pages: 170-182
Piggott MD, Pain CC, Gorman GJ, 2008, Unstructured adaptive meshes for ocean modeling, Ocean modeling in an eddying regime, Editors: Hecht, Hasumi, Hecht, Hasumi, Publisher: Amer Geophysical Union, Pages: 383-408, ISBN: 9780875904429
Farrell PE, Gorman GJ, Piggott MD, et al., 2007, Some problems with quadratic fitting algorithm for Hessian recovery in the context of anisotropic mesh optimisation, International Conference on Adaptive Modeling and Simulation (ADMOS)
Piggott MD, Pain CC, Gorman GJ, et al., 2007, Multi-scale ocean modelling with adapting unstructured grids, CLIVAR Exchanges, Vol: 12, Pages: 21-23, ISSN: 1026-0471
Gorman GJ, Piggott MD, Pain CC, 2007, Shoreline approximation for unstructured mesh generation, Computers & Geosciences, Vol: 33, Pages: 666-677
Wells MR, Allison PA, Piggott MD, et al., 2007, Numerical modeling of tides in the late Pennsylvanian Midcontinent seaway of North America with implications for hydrography and sedimentation, JOURNAL OF SEDIMENTARY RESEARCH, Vol: 77, Pages: 843-865, ISSN: 1527-1404
A novel numerical model (the Imperial College Ocean Model, ICOM) is used to simulate tidal circulation in shallow epicontinental seas connected to large, open oceans. ICOM is validated using the present-day North Sea and applied to predict tidal range in the late Pennsylvanian Midcontinent Seaway (LPMS) of North America. The model simulates the effect of the principal tidal constituents (astronomical tides) as well as the tide propagating from the adjacent open ocean (co- oscillating tide). Two ‘‘base-case’’ Pennsylvanian paleogeographies were tested: (1) a maximum sea-level highstand and (2) the early stages of a transgression. Sensitivity tests determined the importance of paleo-water depth and coastline uncertainty on the prediction of tidal range. During the highstand, tidal ranges in the craton interior (Midcontinent Shelf, Illinois and Appalachian basins) are consistently predicted as microtidal (, 2 m tidal range). Such low tidal ranges would have inhibited water-body mixing in the LPMS, promoting stratification. This, combined with the influx of oxygen-poor water from the Permian Basin to the west and high organic input from tropical rivers, may have contributed to the deposition of ‘‘core’’ black shales in LPMS cyclothems. Conversely, a mesotidal to macrotidal diurnal (once-daily tide) regime is predicted for the early transgression in a large-scale embayment in eastern Kansas due to resonant amplification of diurnal tidal constituents. Pennsylvanian strata here have been ascribed to a mesotidal to macrotidal setting and include cyclic rhythmites that suggest a strongly diurnal system, as predicted by ICOM.
Power PW, Pain CC, Piggott MD, et al., 2006, Adjoint A Posteriori Error Measures for Anisotropic Mesh Optimisation, Computers & Mathematics with Applications, Vol: 52, Pages: 1213-1242
Fang F, Piggott MD, Pain CC, et al., 2006, An adaptive mesh adjoint data assimilation method, Ocean Modelling, Vol: 15, Pages: 39-55, ISSN: 1463-5003
Power PW, Piggott MD, Fang F, et al., 2006, Adjoint goal-based error norms for adaptive mesh ocean modelling, Ocean Modelling, Vol: 15, Pages: 3-38, ISSN: 1463-5003
Gorman GJ, Piggott MD, Pain CC, et al., 2006, Optimisation based bathymetry approximation through constrained unstructured mesh adaptivity, Ocean Modelling, Vol: 12, Pages: 436-452, ISSN: 1463-5003
Power PW, Piggott MD, Fang F, et al., 2006, Adjoint goal-based error norms for adaptive mesh ocean modelling, Ocean Modelling, Vol: 15, Pages: 3-38, ISSN: 1463-5003
Piggott MD, Pain CC, Gorman GJ, et al., 2005, <i>h</i>, <i>r</i>, and <i>hr</i> adaptivity with applications in numerical ocean modelling, OCEAN MODELLING, Vol: 10, Pages: 95-113, ISSN: 1463-5003
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- Citations: 69
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