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Title: Application of two-dimensional cellular automaton lattice-gas models to the simulation of hydrodynamics
Author: Wylie, Brian J. N.
Awarding Body: University of Edinburgh
Current Institution: University of Edinburgh
Date of Award: 1990
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Hydrodynamic equations are notoriously difficult to solve, both analytically and computationally, therefore less complicated methods, drawing on the power of cellular automata and lattice-gases, are introduced. Their combined ability to capture the fundamental properties of fluid dynamics in an inherently simple manner is discussed. The FHP7 cellular automation lattice-gas model of Frisch, Hasslacher and Pomeau, which will form the basis for the subsequent simulations, is described in detail, with a more general covering of the associated models. The scalable and flexible computational power of the transputer-based ECS multicomputer, and how this may be applied to the lattice-gas simulations at hand is addressed. The distributed multiprocessor architecture provides unique challenges, such that the implementation might achieve its potential. It is found that a straightforward one-dimensional geometric decomposition of the lattice, in conjunction with the loosely-synchronous nature of the distributed update, provides a natural load-balancing, and highly scalable efficiency. Visualisation of the development of the hydrodynamic features captured by the simulations, such that their content may be clearly extracted is also addressed. Many interesting transient and dynamic features, often occurring on time-scales which make their analysis by other methods difficult, are easily identified. Those occasionally found to be the result of artifacts, perhaps in the initialisation of the simulation are quickly identified, such that the simulations may be refined. Elementary static systems and flows are designed, such that the ability of the FHP7 lattice-gas to model incompressible hydrodynamics, and its multicomputer implementation, are verified against the theoretically and experimentally expected behaviour. Subsequently, more complex flow configurations involving obstructions and jets, generally beyond the limits of current analytic techniques are constructed, and found to qualitatively match experimental visualisations. No lattice-gases are currently known to accurately model compressible fluid dynamics completely, and the ultimate cause of this limitation still requires clarification. The behaviour of the FHP7 lattice-gas, in réimes where compressibility effects are expected to be important, is investigated with the aim of identifying those aspects of its microdynamics which cause breakdown of its macrodynamics.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available