  In this study we present a free-boundary problem for an active liquid crystal
based on the Beris-Edwards theory that uses a tensorial order parameter and
includes active contributions to the stress tensor to analyse the rich defect
structure observed in applications such as the Adenosinetriphosphate (ATP)
driven motion of a thin film of an actin filament network. The small aspect
ratio of the film geometry allows for an asymptotic approximation of the
free-boundary problem in the limit of weak elasticity of the network and strong
active terms. The new thin film model captures the defect dynamcs in the bulk
as well as wall defects and thus presents a significant extension of previous
models based on the Lesli-Erickson-Parodi theory. Analytic expression are
derived that reveal the interplay of anchoring conditions, film thickness and
active terms and their control of transitions of flow structure.
