  Using fundamental-measure density functional theory we investigate entropic
wetting in an asymmetric binary mixture of hard spheres with positive
non-additivity. We consider a general planar hard wall, where preferential
adsorption is induced by a difference in closest approach of the different
species and the wall. Close to bulk fluid-fluid coexistence the phase rich in
the minority component adsorbs either through a series of first-order layering
transitions, where an increasing number of liquid layers adsorbs sequentially,
or via a critical wetting transition, where a thick film grows continuously.
