  The divergence-free nature of Bessel beams can be harnessed to effectively
trap optical vortices in free space laser propagation. We show how to generate
arbitrary vortex configurations in Bessel traps to investigate few-body vortex
interactions within a dynamically-evolving fluid of light, which is a formal
analog to a non-interacting Bose gas. We implement--theoretically and
experimentally--initial conditions of vortex configurations first predicted in
harmonically-trapped quantum fluids, in the limit of weak atomic interactions,
and model and measure the resultant dynamics. These hard trap dynamics are
distinct from the harmonic trap predictions due to the non-local interactions
that occur among the hard wall boundary and steep phase gradients that nucleate
other vortices. By simultaneously presenting experimental demonstrations with
the theoretical proposal, we validate the potential application of using Bessel
hard wall traps as testing grounds for engineering few-body vortex interactions
within trapped, two-dimensional compressible fluids.
