A “test of concept” comparison of aerodynamic and mechanical resuspension mechanisms for particles deposited on field rye grass (Secale cercele).—Part 2. Threshold mechanical energies for resuspension particle fluxes

Kinetic energy from the oscillatory impacts of the grass stalk against a stationary object was measured with a kinetic energy measuring device. These energy inputs were measured as part of a resuspension experiment of uniform latex microspheres deposited on a single rye grass seed pod in a wind tunnel. The experiment was designed to measure resuspension from aerodynamic (viscous and turbulent) mechanisms compared to that from mechanisms from mechanical resuspension resulting from the oscillatory impact of the grass hitting a stationary object. The experiment was run for deposited spherical latex particles with diameters from 2 to 8.1 μm. Wind tunnel tests were run for wind speeds from 2 to 18.5 m s−1 and a turbulence intensity (root-mean-square fluctuation wind speed/mean wind speed) of 0.1. Our experiments showed the following: • Threshold mechanical energy input rates increased from 0.04 to 0.2 μJ s−1 for resuspension of spherical polystyrene latex particles from 2 to 8.1 μm diameter.• Kinetic energy flux generated by mechanical impact of the wind-driven oscillating grass was found to be highly sensitive to slightly different placements and grass morphology.• The kinetic energy input by impaction of the grass against a stationary cylinder is roughly proportional to the kinetic energy flux of the wind.