  We examine the structural and dynamic properties of confined binary
hard-sphere mixtures designed to mimic realizable colloidal thin films. Using
computer simulations, governed by either Newtonian or overdamped Langevin
dynamics, together with other techniques including a Fokker-Planck
equation-based method, we measure the position-dependent and average
diffusivities of particles along structurally isotropic and inhomogeneous
dimensions of the fluids. At moderate packing fractions, local single-particle
diffusivities normal to the direction of confinement are higher in regions of
high total packing fraction; however, these trends are reversed as the film is
supercooled at denser average packings. Auxiliary short-time measurements of
particle displacements mirror data obtained for experimental supercooled
colloidal systems. We find that average dynamics can be approximately predicted
based on the distribution of available space for particle insertion across
orders of magnitude in diffusivity regardless of the governing microscopic
dynamics.
