Computational Modelling Group

A Fast Multipole Method for the Bessel potential

Marc Molinari, Simon Cox (Investigators), Neil O'Brien

The fast multipole method (FMM) proposed by Greengard and Rokhlin provides a method by which the O(N-squared) many-body problem can be reduced to O(N) complexity. In this project, a multipole method is developed to calculate the energy of a system of vortices in a high temperature superconductor, where the many-body interactions give rise to rich and complex physics. The method developed here is suitable for systems where the interactions are governed by a Bessel potential rather than the usual logarithmic potentials occurring in gravitational and electrostatic problems. We derive and apply vectorised forms of the Gegenbauer addition formulae in order to achieve the O(N) scaling associated with fast multipole methods.

B-meson coupling with relativistic heavy quarks

Jonathan Flynn (Investigator), Ben Samways, Dirk Broemmel, Patrick Fritzsch

We non-perturbatively compute the coupling between B* and B pi meson states relying on relativistic heavy quarks and domain wall light fermions. The coupling is of importance for an effective description of hadronic heavy meson decays.

Cavity-Mediated Cooling

Peter Horak, Timothy Freegarde (Investigators), Andre Xuereb

Optical resonators enhance the interaction of light with matter while simultaneously acting as a temporal buffer. Both effects can be exploited to generate light-induced friction, or cooling, forces on atoms, molecules, or micromirrors. We investigate various aspects of these effects through numerical simulations, assisted by approximate analytical models, in this EPSRC and ESF sponsored project.

Cellular Automata Modelling of Membrane Formation and Protocell Evolution

Seth Bullock (Investigator), Stuart Bartlett

We simulated the meso-level behaviour of lipid-like particles in a range of chemical and physical environments. Self-organised protocellular structures can be shown to emerge spontaneously in systems with random, homogeneous initial conditions. Introducing an additional 'toxic' particle species and an associated set of synthesis reactions produced a new set of ecological behaviours compared to the original model of Ono and Ikegami.

Cosmological evolution of supermassive black holes in the centres of galaxies

Anna Kapinska (Investigator)

Radio galaxies and quasars are among the largest and most powerful single objects known and are believed to have had a significant impact on the evolving Universe and its large-scale structure. Their jets inject a significant amount of energy into the surrounding medium, hence they can provide useful information in the study of the density and evolution of the intergalactic and intracluster medium. The jet activity is also believed to regulate the growth of massive galaxies via the AGN feedback. In this project, through the use of numerical simulations, I explore the intrinsic and extrinsic physical properties of the population of Fanaroff-Riley II (FR II) objects, i.e. their kinetic luminosities, lifetimes, and central densities of their environments. This allows one to investigate evolution of these radio sources across cosmic time, and to discuss the significance of the impact of these sources on the evolving Universe.

Designer 3D Magnetic Mesostructures

Hans Fangohr (Investigator), Matteo Franchin, Andreas Knittel

A new electrodeposition self-assembly method allows for the growth of well defined mesostructures. This project's aim is to use this method in order to fabricate supraconducting and ferromagnetic mesostructures. Numerical methods based on well-established models are used in order to characterise the grown structures.

Discrete ECogeomorphic Aeolian Landscape (DECAL) modelling

Joanna Nield (Investigator)

DECAL is a cellular automaton based model which incorporated mutual feedback processes between geomorphic forcing and ecological growth to investigate fundamental controls, self-organising and non-linear behaviour in semi-arid aeolian dune environments. This project explores landscape evolution and disturbance response, developing a phase-space in which dune fields can be quantified.

Gravitational waves from neutron stars

Ian Hawke (Investigator)

Gravitational waves, once detected, will give information about the extremes of space and time. Compact objects such as neutron stars are perfect locations for generating such waves.

Hadronic structure on the computer

Jonathan Flynn (Investigator), Dirk Broemmel, Thomas Rae, Ben Samways

In experiments at the Large Hadron Collider (LHC) at CERN, Geneva, the interactions that occur between the colliding particles (protons in this case) can be factorised into a simple scattering between two constituent particles, called quarks, followed by a hadronisation process, which describes the dynamics of forming the bound proton states. Quarks are particles within the proton that bind to form composite particles (hadrons) such as a proton. The scattering process can be computed relatively easily, but hadronisation is intrinsically non-perturbative and hard to calculate. Lattice QCD (computer simulation of QCD on a discrete space-time lattice) provides our only known first-principles and systematically-improvable method to address problems like hadronisation. This project uses Iridis to extract parton distribution amplitudes which are experimentally inaccessible, but needed to describe the quark structure of hadrons.

How far can we stretch the MARTINI?

Syma Khalid (Investigator), Ric Gillams

To date, coarse-grained lipid models have generally been parameterised to ensure the correct prediction of structural properties of membranes, such as the area per lipid and the bilayer thickness. The work described here explores the extent to which coarse-grained models are able to predict correctly bulk properties of lipids (phase behaviour) as well as the mechanical properties, such as lateral pressure profiles and stored elastic stress in bilayers. Such an evaluation is crucial for understanding the predictive capabilities of coarse-grained models.

Kaon to two pion decays in lattice QCD

Jonathan Flynn (Investigator), Elaine Goode, Dirk Broemmel

We calculate kaon decay amplitudes on the lattice so we may compare the Standard Model to experiment.

Meshless Methods for Photonic Crystal Modelling

Kamal Djidjeli, Marc Molinari, Simon Cox (Investigators), Neil O'Brien, Elizabeth Hart

We apply meshless methods to the problems of simulating photonic crystals. The meshless methods utilise compactly-supported radial basis functions (CSRBFs) and offer a promising alternative to the conventional plane-wave expansion method for calculating the band structure of photonic crystals.

Modelling micromagnetism at elevated temperature

Hans Fangohr (Investigator), Dmitri Chernyshenko

We aim to develop a multiscale multiphysics model of
micromagnetism at elevated temperatures with atomistic simulations for
material parameter. The tool will be used to guide the development of the next generation magnetic data storage technology: heat assisted magnetic recording.

Multiscale modelling of biological membranes

Jonathan Essex (Investigator), Mario Orsi

Biological membranes are complex and fascinating systems, characterised by proteins floating in a sea of lipids. Biomembranes, besides being the fundamental structures employed by nature to encapsulate cells, play crucial roles in many phenomena indispensable for life, such as growth, energy storage, and in general information transduction via neural activity. In this project, we develop and apply multiscale computational models to simulate biological membranes and obtain molecular-level insights into fundamental structures and phenomena.

Network Analysis of Roman Transport Routes in the Imperial Roman Mediterranean

David Potts

This research is designed to explore the nature of the relationships between Portus, Rome, and other selected ports in the Mediterranean and to establish patterns and the changing nature of trading networks derived from the distribution of known Roman artefacts.

Nmag - computational micromagnetics

Hans Fangohr, Thomas Fischbacher (Investigators), Matteo Franchin, Andreas Knittel, Maximilian Albert, Dmitri Chernyshenko, Massoud Najafi, Richard Boardman

Nmag is a micromagnetic simulation package based on the general purpose multi-physics library nsim. It is developed by the group of Hans Fangohr and Thomas Fischbacher in the School of Engineering Sciences at the University of Southampton and released under the GNU GPL.

Non-Perturbative Renormalisation on the Lattice

Jonathan Flynn (Investigator), Dirk Broemmel, Thomas Rae

In this project we compute renormalisation factors for various physical observables in a non-perturbative lattice framework. Renormalisation hereby arises due to a fundamental scale dependence of the physical processes.

Nonequilibrium Dynamics of Atomic Gases in Optical Lattices

Sophie Marika Reed

Many-body, quantum systems exhibit emergent properties which allows for quantum events to influence properties on macroscopic scales. Such emergent properties are studied using stochastic phase-space techniques.

Nonlinear Optics in Structured Material

Peter Horak, Neil Broderick (Investigators)

Structured materials such as photonic crystals, optical fibres, Bragg gratings etc. are the ideal material for nonlinear optics. Properly engineered materials allows one to control which nonlinear interactions are observed and enhanced whilst other nonlinear interactions can be neglected. This work looks both at fundamental ideas as well as the fabrication of devices for advanced telecommunications.

Numerical Elastic Neutron Stars

Ian Hawke, Ian Jones (Investigators), Andrew Penner

We study the gravitational wave forms that radiate from an asymmetric neutron star using an elasto-hydrodynamic model.

OCCASION: Overcoming Capacity Constraints - A Simulation Integrated with Optimisation for Nodes

Tolga Bektas (Investigator)

OCCASION is a collaboration between TRG and the Schools of Mathematics and Management. The project's objective is to identify and investigate innovative methods of increasing the capacity of nodes (i.e. junctions and stations) on the railway network, without substantial investment in additional infrastructure. To this end, a state-of-the-art review of recent and ongoing work in this area will be conducted, followed by the development of tools to (i) assess existing levels of capacity utilisation at nodes, and (ii) investigate options for re-routeing and re-scheduling trains, with a view to reducing capacity utilisation levels. These tools will be used in combination to develop solutions delivering reduced levels of capacity utilisation, and thus increases in capacity and/or service reliability. Incremental changes to existing railway technologies (e.g. improved points) and operating practice (e.g. relaxations of the Rules of the Plan) will be investigated, as will concepts from other modes (e.g. road and air transport) and sectors (e.g. production scheduling).

Partial Discharge Signal Extraction using Spectral Methods

Condition based maintenance of 3 phase belted cables is increasing in demand as asset lifetimes approach their end...(some more info on the relevance of analysing belted cables).
The application of hard thresholding methods for Partial Discharge [PD] data extraction in high noise-ratio signals may produce series of PD trains with missing events and conversely correct events interlinked with noise. Subsequent analysis of the series will potentially be fraudulent and may lead to inaccurate conclusions. In this work, spectral methods for PD data extraction from very noisy environments are presented and a previously derived PD source classification technique is employed. Tests were conducted on a large set of wide bandwidth field data from three phase belted cables placed around London (UK) and Cyprus, and compared with accelerated aging experimental data. In the search of deeper insights, the deterministic origins of the produced sets of spike trains are explored and some linear and non-linear characteristics derived.

Selection pressure for language and theory-of-mind in monkeys

Jason Noble (Investigator)

To what extent are the alarm calls of putty-nosed monkeys likely to be a good model for human language evolution? Simulation is used to classify evolutionary trajectories as either plausible or implausible, and to put lower bounds on the cognitive complexity required to perform particular behaviours.

Self-Force and Black Hole Inspirals

Sam Dolan (Investigator)

We use IRIDIS to compute the self-force acting on a solar-mass black hole orbiting a supermassive black hole.

Simulating Hydro-geomorphic Changes in European Climate Hotspots

John Dearing (Investigator), Ying Wang

This project will simulate the behaviour of hydro-geomorphological processes in a fluvial system over decadal timescales is an important basis for research on catchment environmental management, especially with regards climate changes and human impacts on fluvial system.

Structured low-rank approximation

Ivan Markovsky

Today's state-of-the-art methods for data processing are model based. We propose a fundamentally new approach that does not depend on an explicit model representation and can be used for model-free data processing. From a theoretical point of view, the prime advantage of the newly proposed paradigm is conceptual unification of existing methods. From a practical point of view, the proposed paradigm opens new possibilities for development of computational methods for data processing.

Surface moisture-induced feedback in aeolian environments

Joanna Nield (Investigator)

This project explores the importance of surface moisture for aeolian processes, particularly feedback between surface moisture and bedform sedimentation and migration.

The application of automated pattern metrics to surface moisture influences on modelled dune field development

Robin Wilson, Joanna Nield (Investigators)

Areas of sand dunes (known as dunefields) develop complex patterns over time. These are influenced by both the past and present environmental conditions, including surface moisture, vegetation distribution and human impact. This project develops a method of automated pattern analysis which allow the patterns produced by a large number of sand dune evolution simulations (performed using the DECAL model) to be quantified over time.

Whisky Code

Ian Hawke (Investigator)

A 3D finite volume code for simulating compact relativistic hydrodynamics.

µ-VIS Computed Tomography Centre

Ian Sinclair, Richard Boardman, Dmitry Grinev, Philipp Thurner, Simon Cox, Jeremy Frey, Mark Spearing, Kenji Takeda (Investigators)

A dedicated centre for computed tomography (CT) at Southampton, providing complete support for 3D imaging science, serving Engineering, Biomedical, Environmental and Archaeological Sciences. The centre encompasses five complementary scanning systems supporting resolutions down to 200nm and imaging volumes in excess of one metre: from a matchstick to a tree trunk, from an ant's wing to a gas turbine blade.