Particle-surface adhesive forces and their role in resuspension phenomena

When considering an aerosol particle which may be returned to the air from a surface under
some flow (resuspended), the forces by which the particle is first adhered to the surface play
a vital role. While these particle-adhesive forces are theoretically understood, the size of
these forces, and the conditions required for resuspension, are difficult to determine or
predict during mathematical resuspension models.
This project aims to investigate the adhesive forces between particles and surfaces, as
well as the factors which may influence these forces. Improvements to mathematical models
for resuspension can then be explored.
During the project, the particle-surface adhesive forces between a range of specimens will
be measured using atomic force microscopy. The effect of varying certain factors, specifically
morphology (roughness), surface energy, and hydrophobicity of the surfaces and particles
will be systematically studied. A range of surfaces and particles will be produced to achieve
this. For surfaces, nanolithography and 3D printing will be utilised, and for particles,
salt and sugar particles will be produced with controlled morphology. Further, relative
humidity will be varied and its effect on the measured force profiles will be determined.

These measurements and findings will inform refinements of a mechanistic model for particle
resuspension and these changes will then be validated through wind tunnel experiments.
By the end of the project, a comprehensive picture of particle-adhesive forces under various conditions will be produced and implemented to produce a more realistic mathematical
model for resuspension that better reflects real world scenarios.