Agglomeration of Oppositely Charged Particles in Nonpolar Liquids
  We study the aggregation of insulating electrically charged spheres suspended in a nonpolar liquid. Regarding the van der Waals interaction as an irreversible sticking force, we are especially interested in the charge distribution after aggregation. Solving the special case of two oppositely charged particles exactly, it is shown that the surface charges either recombine or form a residual dipole, depending on the initial condition. The theoretical findings are compared with numerical results from Monte Carlo simulations. 
Jochen H. Werth, Henning Knudsen, Haye Hinrichsen