  Particle impaction on a cylinder in a cross flow is investigated with the use
of Direct Numerical Simulations (DNS) and with a focus on the effect of
turbulence on the impaction efficiency. The turbulence considered is isotropic
homogeneous turbulence with varying integral scales. It is found that for
particles with Stokes numbers in the boundary stopping mode there is up to 10
times more front side impaction for turbulence with a large integral scale than
for a corresponding laminar flow. For decreasing integral scales the effect of
the turbulence on front side particle impaction efficiency is decreasing. The
back side impaction efficiency is also found to be influenced by the
turbulence, but for the back side the strongest effect, and largest impaction
efficiency, is found for small integral scales.
