  A comprehensive parametric study of plasma-grain interaction for
non-Maxwellian streaming ions in steady-state employing particle-in-cell
simulations is delineated. Instead of considering the inter-grain interaction
potential to be the linear sum of isolated grain potentials, we incorporate the
numerical advancement developed fully for grain shielding by including
nonlinear contributions from the plasma and shadowing effect. The forces acting
on grains versus inter-grain distance, streaming velocity of the ions, and
impact of trapped ions density (number) are characterized for non- Maxwellian
ions in the presence of charge-exchange collisions. It is found that the
nonlinear plasma response considerably modifies the plasma-grains interaction.
Unlike the stationary plasma case, for two identical grains separated by a
distance in the presence of streaming ions, the electrostatic force is neither
repulsive for all grain separations nor equivalent to the force due to one
isolated grain. Inadequacy of the linear response formalism in dealing with the
systems having very large grain charges is also discussed. The smallest
inter-grain separation for which the role of the shadow effect can be ignored
is reported.
