  Producing dense and homogeneous powder layers with smooth free surface is
challenging in additive manufacturing, as interparticle cohesion can strongly
affect the powder packing structure and therefore influence the quality of the
end product. We use the Discrete Element Method to simulate the spreading
process of spherical powders and examine how cohesion influences the
characteristics of the packing structure with a focus on the fluctuation of the
local morphology. As cohesion increases, the overall packing density decreases,
and the free surface roughness increases, which is calculated from digitized
surface height distributions. Local structural fluctuations for both quantities
are examined through the local packing anisotropy on the particle scale,
obtained from Vorono\"{\i} tessellation. The distributions of these
particle-level metrics quantify the increasingly heterogeneous packing
structure with clustering and changing surface morphology.
