The rate of aggregation is in general determined by the frequency of collisions and
the
probability of cohesion during collision. If the collisions are caused by
Brownian motion, the process is called perikinetic aggregation.
Source:
PAC, 1972, 31, 577
(Manual of Symbols and Terminology for Physicochemical Quantities and Units, Appendix
II: Definitions, Terminology and Symbols in Colloid and Surface Chemistry)
on page 610