  It is widely recognized that the structure of porous media is of relevance
for a variety of mechanical and physical phenomena. The focus of the present
work is on capillarity, a pore-scale process occurring at the micron scale. We
attempt to characterize the influence of pore shape for capillary infiltration
by means of Lattice Boltzmann simulations in 2D with reactive boundaries
leading to surface growth and ultimately to pore closure. The systems under
investigation consist of single channels with different simplified
morphologies: namely, periodic profiles with sinusoidal, step-shaped and
zig-zag walls, as well as constrictions and expansions with rectangular, convex
and concave steps. This is a useful way to decompose the complexity of typical
porous media into basic structures. The simulations show that the minimum
radius alone fails to characterize properly the infiltration dynamics. The
structure of the channels emerge as the dominant property controlling the
process. A factor responsible for this behavior is identified as being the
occurrence of pinning of the contact line. It turns out that the optimal
configuration for the pore structure arises from the packing of large particles
with round shapes. In this case, the probability to have flow paths wide and
straight is higher. Faceted surfaces presenting sharp edges should be avoided
because of the phenomenon of pinning near narrow-to-wide parts. This study is
motivated by the infiltration of molten metals into carbon preforms. This is a
manufacturing technique for ceramic components devised to advanced
applications. Guidelines for experimental work are discussed.
