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), Patrick Fritzsch, Dirk Broemmel

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 simulate 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. We aim to take the current model further and explore more complex chemical scenarios in which a broad range of evolutionary behaviours will be exhibited.

Chaotic Analysis of Partial Discharge

Paul Lewin

The deterministic character of PD pulses predicted by theory can experimentally (real and numerical) be shown to be existent. Finding characteristic patterns in phase space enables field-data PD detection with high reliability.

Computational electromagnetic modelling of 3D photonic structures

Marc Molinari, Darren Bagnall, Simon Cox (Investigators), Asa Asadollahbaik, Elizabeth Hart

Nano-structured materials can provide very specific and often very special optical effects which can be exploited for a large range of optical applications including wavelength filters, LEDs, micro-lasers, HDTV, solar-cell coatings, optical high-Q fibres, diffraction gratings, polarisation devices, optical switches, etc. This research in “Computational Electromagnetic Modelling of 3D Photonic Structures” aims to address the need for accurate and fast three-dimensional modelling, simulation and analysis processes in the photonics industry. A FEM/FDTD software suite will be developed to simulate Maxwell’s field equations and thin-film quantum effects (plasmons) in the visible and near-infrared EM frequency spectrum. The results obtained from running the software on suitable compute clusters will then be compared to the analysis results of experimentally manufactured materials. We will investigate structures occurring in nature such as iridescent butterfly wings, white/black reflecting beetle shells, etc., and aim to optimise artificially designed structures with periodic, quasi-periodic and random configurations.

Computational Methods for Aircraft Noise Prediction

Gwenael Gabard (Investigator), Albert Prinn

The aim of this project is to develop and test an efficient flow acoustics solver based on the finite element method and the potential flow theory.

DePuy Technology Partnership

Mark Taylor (Investigator), Adam Briscoe

This initiative concerns the transfer of knowledge between three key institutions (University of Southampton, University of Leeds and University of Hamburg) and DePuy International limited. The project is concerned with the ongoing advancement of technology used in orthopaedic devices.

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.

Efficient algorithms for liquid crystal alignment

Giampaolo D'Alessandro, Timothy Sluckin (Investigators)

We have developed an efficient algorithm to determine the liquid crystal alignment in the absence of defects. The aim of this project is to extend this algorithm to include defects.

Fluid Loads and Motions of Damaged Ships

Dominic Hudson, Ming-yi Tan (Investigators), Christian Wood, James Underwood, Adam Sobey

An area of research currently of interest in the marine industry is the effect of damage on ship structures. Research into the behaviour of damaged ships began in the mid nineties as a result of Ro-Ro disasters (e.g. Estonia in 1994). Due to the way the Estonia sank early research mainly focused on transient behaviour immediately after the damage takes place, the prediction of capsize, and of large lateral motions. Further research efforts, headed by the UK MoD, began following an incident where HMS Nottingham ran aground tearing a 50m hole from bow to bridge, flooding five compartments and almost causing the ship to sink just off Lord Howe Island in 2002. This project intends to answer the following questions:
“For a given amount of underwater damage (e.g. collision or torpedo/mine hit), what will be the progressive damage spread if the ship travels at ‘x’ knots? OR for a given amount of underwater damage, what is the maximum speed at which the ship can travel without causing additional damage?”

Generating Optimal Ensembles of Earth System Models

Simon Cox (Investigator), Elizabeth Hart, Andras Sobester

GENIE is an Earth system model of intermediate complexity. As with other climate models, the tuning of its parameters is essential for providing reliable long-term forecasts of Earth system behaviour. We apply a multi-objective optimization algorithm to the problem. The aim of the tuning exercise is to find the optimal values for the free parameters that produce and euqilibrium model end state with the closest fit to equivalent observational data.

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.

Immunotherapy Research: Modelling MHC Class I Complex Assembly

Timothy Elliott, Jorn Werner (Investigators), Alistair Bailey

This project uses mathematical modelling and simulation to investigate mechanisms by which our cells process and present biological information that is used by our immune system to distinguish between healthy and diseased cells.

Investigation of acoustic radiation forces on micro-particles and cells in ultrasonic particle manipulation

Martyn Hill (Investigator), Puja Mishra

A Finite Element model is developed to investigate the force generated on a particle of arbitrary geometry and composition in a sound field. The model overcame the drawbacks of existing analytical solutions of size restriction and provided the flexibility of particle representation. This suggested useful results on shape dependency, effect of elasticity of particle and dominancy of nucleus in a cell in estimating the force on a single particle.

Mathematical modelling of plant nutrient uptake

Tiina Roose (Investigator)

In this project I will describe a model of plant water and nutrient uptake and how to translate this model and experimental data from the single root scale to the root branching structure scale.

Measuring biomolecules - improvements to the spectroscopic ruler

Pavlos Lagoudakis, Tom Brown (Investigators), Jan Junis Rindermann, James Richardson

The spectroscopic ruler is a technique to measure the geometry of biomolecules on the nm scale by labeling them with pairs of fluorescent markers and measuring distance dependent non-radiative energy transfer between them. The remaining uncertainty in the application of the technique originates from the unknown orientation between the optical dipole moments of the fluorescent markers, especially when the molecule undergoes thermal fluctuations in physiological conditions. Recently we introduced a simulation based method for the interpretation of the fluorescence decay dynamics of the markers that allows us to retrieve both the average orientation and the extent of directional fluctuations of the involved dipole moments.

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 mechanoreceptor reaction to tissue deformation

Mark Taylor (Investigator), Gwen Palmer

This project involved the modelling of a piece of knee joint capsule, which will produce an electrical output when mechanically stimulated. The model is based on expermental work carried out by P. Grigg and A.H. Hoffman (1982).

Modelling neuronal activity at the knee joint

Mark Taylor, Tiina Roose (Investigators), Gwen Palmer

The function of the knee joint is reliant on proprioception, which involves the response of nerve endings in the tissues at the joint. This project will be concentrating on the neuronal activity, caused by mechanical stimuli, of the more common receptors found at the knee (Ruffini, Paciniform, Golgi and Nociceptor).

There are three stages to this project:
1. Modelling the behaviour of each individual receptor, with the use of the Hodgkin-Huxley model [1].
2. These models will then be applied to the soft tissues around a knee, where a global deformation of the tissue will result in local stimulation of receptors.
3. The soft tissue models will then be applied to structures in the knee.

[1] - Hodgkin, A.L. and A.F. Huxley, A quantitative description of membrane current and its application to conduction and excitation in nerve. Journal of Physiology, 1952. 117: p. 500-544.

Multi-objective design optimisation of coronary stents

Neil Bressloff, Georges Limbert (Investigators), Sanjay Pant

Stents are tubular type scaffolds that are deployed (using an inflatable balloon on a catheter), most commonly to recover the shape of narrowed (diseased) arterial segments. Despite the widespread clinical use of stents in cardiovascular intervention, the presence of such devices can cause adverse responses leading to fatality or to the need for further treatment. The most common unwanted responses of inflammation are in-stent restenosis and thrombosis. Such adverse biological responses in a stented artery are influenced by many factors, including the design of the stent. This project aims at using multi-objective optimisation techniques to find an optimum family of coronary stents which are more resistant to the processes of in-stent restenosis (IR) and stent thrombosis (ST).

MXL Project

Mark Taylor, Junfen Shi (Investigators)

‘MXL’ is short for “Enhanced patient safety by computational Modelling from clinically available X-rays to minimise the risk of overload and instability for optimised function and Longevity”. This is an international EU-funded project which the Bioengineering Sciences Research Group at Southampton is involved in. For more information, visit http://www.m-x-l.eu

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 Optical Pulse Propagation

Peter Horak, Francesco Poletti (Investigators)

The work is concerned with the propagation of high-power short-pulse propagation in microstructured fibres or waveguides. Dispersion properties and optical nonlinearities are exploited for pulse shaping techniques in space, time, and frequency. Investigated microstructures include silica or soft-glass templates, gas-filled capillaries, and semiconductor-filled fibres, and optical wavelengths range from the X-ray to the mid-infrared regime.

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.

Prediction of orifice flow flooding rates through generic orifices

Dominic Hudson, Ming-yi Tan (Investigators), Christian Wood, Adam Sobey

This presearch concentrates on the modelling of compartment flooding rates following the occurrence of damage in a ship's side shell. Typical state of the art flooding models use Torricelli’s formula to calculate flooding rates using a constant co-efficient of discharge (Cd). Based on Bernoulli’s theorem, turbulence and viscosity effects are not included using a Cd independent of damage shape or size. Previous work indicates that this assumption over-simplifies the problem to an extent where the flooding rates used for calculation are in error. This project will use CFD validated by experiment to calculate flooding rates for a large number of cases from which a 'krigged' response surface will be generated. Validity of the subsequent response surface will be interrogated.

Real-time CFD for helicopter flight simulation

Kenji Takeda (Investigator), James Kenny

Project aims to show how real-time computational fluid dynamics (CFD) could be used to improve the realism of helicopter flight simulators.

Soft x-ray science on a tabletop

Peter Horak, Jeremy Frey, Bill Brocklesby (Investigators), Patrick Anderson

Complex numerical simulations are being performed to aid experimentalists at Southampton realize the next generation of high brightness tabletop sources of coherent soft x-rays.


Solar Tracking Strategies

This project proposes the use of short range cloud dynamics predictions as a novel method of active tracking for optimal positioning of photovoltaic arrays by use of a hybrid model of ground
based and remotely sensed data.

Statistical model of the knee

Mark Taylor (Investigator), Francis Galloway, Prasanth Nair

Development of methods for large scale computational testing of a tibial tray incorporating inter-patient variability.

Stochastic computational methods for aero-acoustics

Gwenael Gabard (Investigator), Martina Dieste

Stochastic methods are used to synthesize a turbulent flow which is then used to model the sound radiated by an airfoil interacting with this turbulence. This approach is faster than performing a complete simulation of the flow field.

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.

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.

The effect of roughness upon turbulent supersonic flows

Neil Sandham (Investigator), Christopher Tyson

Understanding the interaction between surface roughness and supersonic air flows are crucial in the design of re-entry vehicles such as the space shuttle. Numerical simulations of these flows has been conducted in order to examine the relationship in order to attempt to achieve a much clearer understanding of the behaviour.

Transition to turbulence in high-speed boundary layers

Neil Sandham (Investigator), Nicola De Tullio

This work is focused on the numerical simulation of hypersonic transition to turbulence in boundary layers. We use direct numerical simulations of the Navier-Stokes equations to analyse the effects of different flow conditions and external disturbances on the transition process. The main objective is to gain insight into the different aspects of transition to turbulence at high speeds, which can lead to the design of new transition models and transition control techniques for high-speed flows.

Vortices in Spinor Bose-Einstein Condensates

Janne Ruostekoski (Investigator), Justin Lovegrove

We numerically study the effect of spin degrees of freedom on the structure of a vortex in a Bose-Einstein Condensate. Such objects are of interest as macroscopic examples of quantum phenomena, as well as for their analogies in other fields, such as cosmology and high energy physics.

Wave-based discontinuous Galerkin methods

Gwenael Gabard (Investigator), Greg Kennedy

Wave-based computational methods are developed to model sound propagation in moving inhomogeneous media.

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.