  The random vortex world-surface model is an infrared effective model of
Yang-Mills dynamics based on center vortex degrees of freedom. These degrees of
freedom carry topological charge through writhe and self-intersection of their
world-surfaces. A practical implementation of the model realizes the vortex
world-surfaces by composing them of elementary squares on a hypercubic lattice.
The topological charge for specifically such configurations is constructed in
the case of SU(3) color. This necessitates a proper treatment of vortex color
structure at vortex branchings, a feature which is absent in the SU(2) color
case investigated previously. On the basis of the construction, the topological
susceptibility is evaluated in the random vortex world-surface ensemble, both
in the confined low-temperature as well as in the deconfined high-temperature
phase.
