Adhesion force measurement and resuspension of glass particles from a wall surface functionalized with well-defined microasperities

The resuspension of microparticles by a turbulent gas flow occurs in many industrial
systems. Industrial surfaces, onto which particles initially adhere, are rarely smooth and
this surface roughness affects their resuspension. Available experimental data on particle
resuspension have been obtained with substrates, whose surfaces are either unaltered or
manually abraded with, for instance, sand blasting. In these experiments, the roughness
elements span a wide size range and are in-homogeneously distributed in space. Surface
functionalization is a modern technique allowing the precise fabrication of a wall surface
with well-characterized microstructures, hence reducing the asperity randomness associated
with conventional abrasion techniques. Taking advantage of surface functionalization, we
present here a new set of reference data, where the wall asperities are represented by a
structured arrangement of micropillars and microcubes. Adhesion force measurements and
particle remaining fraction against gas velocity, at Reynolds number up to 8000, are reported
for one reference and two artificially roughened substrates. Laboratory measurements show
that the microasperities have little to moderate effect on the mean adhesion force and the
threshold velocity, at which half of the 100 μm particles resuspend. The standard deviations
are, however, significantly affected. The presented results will primary contribute to the
improvement of resuspension models, which until now rely on a simplified representation of
the surface roughness elements.