  Active gels play an important role in biology and in inspiring biomimetic
active materials, due to their ability to change shape, size and create their
own morphology; the relevant mechanics behind these changes is driven by
self-contraction and liquid flow. Here, we couple contraction and liquid flow
within a nonlinear mechanical model of an active gel disc to discuss how
contraction dynamics inherits length scales which are typical of the liquid
flow processes. The cylindrically symmetric model we present, which
recapitulate our previous theoretical modeling in its basic lines, reveals that
when also liquid flow is taken into account, the aspect ratio of the disc is
not the only geometrical parameter which characterizes the contraction dynamics
of the gel. The analyses we present provide important insights into the
dependence of contraction dynamics on geometry and allow to make some progress
in designing materials which can be adapted for different applications in soft
robotics.
