| dc.description.abstract | This thesis describes investigations of several complex fluid effects., including
hydrodynamic spinodal decomposition, viscous instability. and self-assembly of a
cubic surfactant phase, by simulating them with a lattice Boltzmann computational
model.
The introduction describes what is meant by the term "complex fluid", and why
such fluids are both important and difficult to understand. A key feature of complex
fluids is that their behaviour spans length and time scales. The lattice Boltzmann
method is presented as a modelling technique which sits at a "mesoscale" level
intermediate between coarse-grained and fine-grained detail, and which is therefore
ideal for modelling certain classes of complex fluids.
The following chapters describe simulations which have been performed using
this technique, in two and three dimensions. Chapter 2 presents an investigation
into the separation of a mixture of two fluids. This process is found to involve several
physical mechanisms at different stages. The simulated behaviour is found to be in
good agreement with existing theory, and a curious effect, due to multiple competing
mechanisms, is observed, in agreement with experiments and other simulations.
Chapter 3 describes an improvement to lattice Boltzmann models of Hele-Shaw
flow, along with simulations which quantitatively demonstrate improvements in both
accuracy and numerical stability. The Saffman-Taylor hydrodynamic instability is
demonstrated using this model.
Chapter 4 contains the details and results of the TeraGyroid experiment, which
involved extremely large-scale simulations to investigate the dynamical behaviour
of a self-assembling structure. The first finite- size-effect- free dynamical simulations
of such a system are presented. It is found that several different mechanisms are
responsible for the assembly; the existence of chiral domains is demonstrated, along
with an examination of domain growth during self-assembly.
Appendix A describes some aspects of the implementation of the lattice Boltzmann
codes used in this thesis; appendix B describes some of the Grid computing
techniques which were necessary for the simulations of chapter 4.
Chapter 5 summarises the work, and makes suggestions for further research and
improvement. | en_US |
