CSR 1-2003 Case-Based Interactive Multimedia Systems for Rheological Science
I. Deliyannis, J. Harvey and M.F. Webster
Multimedia environments are utilised to construct presentation systems, introducing some advanced interactive features.
Some aspects of this research involve the organisation, presentation and interaction of complex industrial case-study data,
arising from Computational Fluid Dynamic simulations and experimental trials (multimedia streams and static instances).
Also, the development of rheological courseware is addressed. Modular interface constructs are employed to facilitate
rapid and sound system-development. Object-oriented practices are deployed, based on an underlying graph structure.
The multimedia nature of the implementation promotes interaction with synchronised animated flow-visualisation data
(Motion-blur, static plots animated through settings, solid-modelling animations). This, in turn, enhances the
understanding of the underlying data. The resulting implementation can be ported to a variety of computer-platforms, or
streamed over Internet connections without compromise in quality or interactivity. Such flexibility of distribution renders
these systems ideal for publishing of scientific content between virtual research communities and industrialists, rendering
e-Learning and e-Research widely accessible in a media-rich interactive form. It is shown how distinct individual
multimedia implementations are constructed and utilised, through a range of industrially-based and educational casestudies.
In addition, the semantic linking of content is discussed and it is shown how this may be achieved through such
merged (linked) multimedia systems (externally, locally - single computer, or over Internet communication channels),
aiding presentation and detailed data interrogation.
Report Titles
CSR 2-2003 A multimedia environment for investigation of experimental and simulated Dough Kneading data sets
I. Deliyannis and M.F. Webster
A detailed industrially-based multimedia case-study is considered, featuring experimental and simulation doughkneading
data-sets. Multimedia environments are employed, creating flexible implementations, whilst dealing with large and
densely interrelated data. This complicated rheological investigation, aided via multimedia technology, spans across various
parameter spaces. These include geometric, fluid-type, speed, depth and stirrer-shape adjustments. Direct data-comparison
across valid combinations is actioned, through multi-menus. Voiceover-streams and multiple navigation-paths are characteristic
features. Multimedia environment-level retiming supports synchronised presentation of non-uniform animations, reducing
re-rendering times. Through multimedia environments, direct system-updates are practical, whilst data-duplication is avoided.
Such implementation enhances the presentation impact-factor of the work. As such, the system supports intelligent interrogation,
that itself, may lead to heightened awareness and meaningful interpretation of the data. Whilst the resulting systems fulfil
base-level presentation requirements over various media, the same systems may be used for further data-evaluation.
Report Titles
CSR 3-2003 High-order Finite Volume Methods for Viscoelastic Flow Problems
M. Aboubacar, T.N. Phillips, H.R.Tamaddon-Jahromi, B.A. Sginerev and M.F. Webster
Two distinct finite volume schemes are presented for solving the system of partial
differential equations describing the flow of viscoelastic fluids. The schemes are
constructed to be second-order accurate in space. The issue of stability is addressed
with respect to the treatment of convection. Numerical examples are presented illustrating
the performance of these schemes on some steady and transient problems that possess analytical solutions.
Report Titles
CSR 4-2003 Second-order Schemes for Steady Weakly Compressible Liquid Flows
I. J. Keshtiban, F. Belblidia and M. F. Webster
We introduce a time-marching Taylor-Galerkin/pressure-correction algorithm to
accommodate weakly compressible flows at low Mach number. Two discrete representations
are proposed to interpolate density: a piecewise-constant form with gradient recovery and a
linear interpolation form, akin to that on pressure. Numerical performance is considered on a
selection of benchmark problems to highlight stability and accuracy properties of both
implementations. Validation bears out the high quality of performance and behaviour of both
compressible flow implementations, at low to vanishing Mach number. Neither linear, nor
constant density interpolations schemes degrade the second-order accuracy of the original
incompressible Taylor-Galerkin/pressure-correction scheme. The piecewise-constant
interpolation scheme is advocated strongly as the preferred method of choice, with its
advantages of order retention, yet efficiency in implementation.
Report Titles
CSR 5-2003 Unified Computational Schemes for Incompressible and Weakly Compressible Flows
I. J. Keshtiban, F. Belblidia and M. F. Webster
A time-marching Taylor-Galerkin finite element algorithm, based on a pressure-correction
method with three fractional stages, is presented. The algorithm is applied in a consistent and
unified manner to weakly compressible and incompressible flows. For the compressible regime,
two types of density interpolation are investigated: a piecewise-constant form with gradient
recovery and a linear interpolation form. The background theory and consistency of the approach
are discussed. Numerical results are presented for high pressure-drop, 4:1 contraction flows,
under planar and axisymmetric frames of reference. Stability and accuracy of the method is
highlighted, bearing out the high quality of performance achieved for both compressible flow
density interpolation schemes, at low to vanishing Mach number. Primarily, we advocate the
piecewise-constant interpolation algorithm.
Report Titles
CSR 6-2003 Algebraic Models of Correctness for Abstract Pipelines
A. C. J. Fox and N. A. Harman
We apply algebraic tools for modelling microprocessors to the specification, implementation,
and verification of an abstract pipelined case study. We employ a model
of time based on counting events by means of a clock. We model systems by iterated
maps that evolve over time from some initial state. We define formal correctness
conditions, and introduce the one-step theorems that can reduce the complexity
of formal verification. The algebraic models provide: (i) modular descriptions of
pipelined systems; (ii) equational correctness criteria; and (iii) equational
specification
and verification techniques for the design of pipelined systems applicable to a
range of software systems.
Report Titles
CSR 7-2003 On the conflict matrix of clause-sets
O. Kullmann
The notion of the conflict matrix of a
conjunctive normal form is introduced,
building a bridge between the addressing
problem and the biclique partition problem
from combinatorics and graph theory, and
the combinatorics of conjunctive normal
forms.
A central tool introduced in this report
is the notion of the hermitian defect of
a conjunctive normal form, and several
connections to the theory of autarkies
are revealed.
Report Titles
CSR 8-2003 Novel Schemes for Steady Weakly Compressible and Incompressible Flows
F. Belblidia, I. J. Keshtiban and M. F. Webster
A Taylor-Galerkin/pressure-correction algorithm is applied in a consistent and a
unified manner to accommodate incompressible and weakly compressible flows. For the
compressible regime, two discrete representations of density are proposed:
a piecewise constant form with gradient recovery and a linear interpolation form. Numerical
performance is considered on a benchmark problem. Stability and accuracy properties of the
method are highlighted for a wide range of low to vanishing Mach number. Primarily, we
advocate the piecewise-constant interpolation algorithm.
Report Titles
CSR 9-2003 Numerical Simulation of Compressible Viscoelastic Liquids
I. J. Keshtiban, F. Belblidia and M. F. Webster
A stable and accurate time-marching pressure-correction/Taylor-Galerkin finite element algorithm is
presented to accommodate low Mach number compressible and incompressible viscoelastic liquid flows.
The algorithm is based on an operator splitting constructive process that discloses three fractional stages.
For the compressible regime, a piecewise-constant density interpolation with gradient recovery is
employed, for which the background theory and consistency of approach are discussed. The scheme is
applied to contraction flows for Oldroyd model fluids, covering entry-exit flows and high pressure-drop
situations. Stability and performance characteristics of the new algorithmic implementation are
highlighted. Solutions are provided for a range of compressible settings, tending to the incompressible
limit at vanishing Mach number.
Report Titles
CSR 10-2003 Consistent Hybrid Finite Volume/Element Formulations: Model and Complex Viscoelastic Flows
M.S. Chandio, K.S. Sujatha and M. F. Webster
The accuracy and consistency of a new cell-vertex hybrid finite element/volume scheme are
investigated for viscoelastic flows. Finite element discretisation is employed for the momentum and
continuity equation, with FV applied to the constitutive law for stress. Here, the interest is to explore
the consequences of utilizing conventional cell-vertex methodology for an Oldroyd-B model and to
demonstrate resulting drawbacks in the presence of complex source terms on structured and
unstructured grids. Alternative strategies worthy of consideration are presented. It is demonstrated
how high-order accuracy may be achieved in steady-state by respecting consistency in the
formulation. Both FE and FV spatial discretisations are embedded in the scheme, with FV triangular
sub-cells referenced within parent triangular finite elements. Both model and complex flow problems
are selected to quantify and assess accuracy, appealing to analysis and experimental validation. The
test problem is that of steady sink flow, a pure extensional flow, which reflects some of the numerical
difficulties involved in solving more generalised viscoelastic flows, where both source and flux terms
may contribute equally. In addition, a complex transient filament-stretching flow is chosen to
compute the evolution of stress fields within liquid bridges. Shortcomings of the various upwinding
schemes are discussed in this context, whilst dealing with such free-surface type problems. Here,
fluctuation distribution alone is advocated and a Lax-scheme is found to deliver accuracy and stability
to the computational results, comparing well with the literature.
Report Titles
CSR 11-2003 Computation of Weakly-Compressible Highly-Viscous Polymeric Liquid Flows
M. F. Webster, I. J. Keshtiban, and F. Belblidia
We introduce a high-resolution time-marching pressure-correction algorithm to
accommodate weakly-compressible highly-viscous polymeric liquid flows at low Mach
number. As the incompressible limit is approached ( Ma Å 0 ), the consistency of the
compressible scheme is highlighted in recovering equivalent incompressible solutions. In
the viscous-dominated regime of low Reynolds number (zone of interest), the algorithm
treats the viscous part of the equations in a semi-implicit form. Two discrete
representations are proposed to interpolate density: a piecewise-constant form with
gradient recovery and a linear interpolation form, akin to that on pressure. Numerical
performance is considered on a number of classical benchmark problems for viscous
polymeric liquid flows to highlight consistency, accuracy and stability properties.
Validation bears out the high quality of performance of both compressible flow
implementations, at low to vanishing Mach number. Neither linear, nor constant density
interpolations schemes degrade the second-order accuracy of the original incompressible
fractional-staged pressure-correction scheme. The piecewise-constant interpolation scheme
is advocated strongly as the preferred method of choice, with its advantages of order
retention, yet efficiency in implementation..
Report Titles