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A. J. Roberts

Publications and source records attributed to A. J. Roberts.

92 records · Page 6Linked to original sources

Initial Conditions for Models of Dynamical Systems

The long-time behaviour of many dynamical systems may be effectively predicted by a low-dimensional model that describes the evolution of a reduced set of variables. We consider the question of how to equip such a low-dimensional model with appropriate initial conditions, so that it faithfully reproduces the long-term behaviour of the original high-dimensional dynamical system. Our method involves putting the dynamical system into normal form, which not only generates the low-dimensional model, but also provides the correct initial conditions for the model. We illustrate the method with several examples. Keywords: normal form, isochrons, initialisation, centre manifold

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Long-wave models of thin film fluid dynamics

Centre manifold techniques are used to derive rationally a description of the dynamics of thin films of fluid. The derived model is based on the free-surface $η(x,t)$ and the vertically averaged horizontal velocity $\avu(x,t)$. The approach appears to converge well and has significant differences from conventional depth-averaged models.

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