A numerical integration method is used to simulate the motion of a gro
up of toner particles under the influence of multiple force fields and
elastic collisions as the particles travel from a developer sleeve to
a paper surface. Forces and force fields acting on the toner particle
s are described in equation form and entered into a personal computer
application program for integration in selectable time steps. A repres
entative simulation is described using a TonerJet print zone as an exa
mple.