 Maximum preferential concentration occurs at formula_8.Particles with formula_9 follow fluid streamlines and particles with formula_10 do not respond significantly to the fluid within the times the fluid motions are coherent.Systems that can be strongly influenced by the dynamics of preferential concentration are aerosol production of fine powders, spray, emulsifier, and crystallization reactors, pneumatic devices, cloud droplet formation, aerosol transport in the upper atmosphere, and even planet formation from protoplanetary nebula.