The covariant approach to LRS perfect fluid spacetime geometries

The dynamics of perfect fluid spacetime geometries which exhibit local rotational symmetry (LRS) are reformulated in the language of a 1 + 3 'threading' decomposition of the spacetime manifold, where covariant fluid and curvature variables are used. This approach presents a neat alternative to the orthonormal frame formalism. The dynamical equations reduce to a set of differential relations between purely scalar quantities. The consistency conditions are worked out in a transparent way. We discuss their various subcases in detail and focus in particular on models with higher symmetries within the class of expanding spatially inhomogeneous LRS models, via a consideration of functional dependences between the dynamical variables.