John Peter Wainwright

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We present a general framework for analyzing spatially inhomogeneous cosmological dynamics. It employs Hubble-normalized scale-invariant variables which are defined within the orthonormal frame formalism, and leads to the formulation of Einstein's field equations with a perfect fluid matter source as an autonomous system of evolution equations and(More)
We study the late time evolution of a class of exact anisotropic cosmological solutions of Einstein's equations, namely spatially homogeneous cosmologies of Bianchi type VII 0 with a perfect fluid source. We show that, in contrast to models of Bianchi type VII h which are asymptotically self-similar at late times, Bianchi VII 0 models undergo a complicated(More)
In this paper we give, for the first time, a complete description of the dynamics of tilted spatially homogeneous cosmologies of Bianchi type II. The source is assumed to be a perfect fluid with equation of state p = (γ − 1)µ, where γ is a constant. We show that unless the perfect fluid is stiff, the tilt destabilizes the Kasner solutions, leading to a(More)
In this paper we investigate asymptotic isotropization. We derive the asymptotic dynamics of spatially inhomogeneous cosmological models with a perfect fluid matter source and a positive cos-mological constant near the de Sitter equilibrium state at late times, and near the flat FL equilibrium state at early times. Our results show that there exists an open(More)
In this paper we give, for the first time, a qualitative description of the asymptotic dynamics of a class of non-tilted spatially homogeneous (SH) cosmologies, the so-called exceptional Bianchi cosmologies, which are of Bianchi type VI −1/9. This class is of interest for two reasons. Firstly, it is generic within the class of non-tilted SH cosmologies,(More)
In this paper we give, for the first time, a complete description of the late-time evolution of non-tilted spatially homogeneous cosmologies of Bianchi type VIII. The source is assumed to be a perfect fluid with equation of state p = (γ − 1)µ, where γ is a constant which satisfies 1 γ 2. Using the orthonormal frame formalism and Hubble-normalized variables,(More)
We consider the late time behaviour of non–tilted perfect fluid Bianchi VII0 models when the source is a radiation fluid, thereby completing the analysis of the Bianchi VII0 models initiated by Wainwright et al in a recent paper. The models exhibit the phenomena of asymptotic self-similarity breaking and Weyl-curvature dominance at late times. The late time(More)
An experimental investigation into the interaction that occurs between an impacting water droplet and a granular bed of loose graded sand has been carried out. High-speed imaging, three-dimensional time-resolved particle tracking, and photogrammetric surface profiling have been used to examine individual impact events. The focus of the study is the(More)