On the use of the Knudsen number and aerosol Knudsen number in the kinetics of Brownian coagulation of aerosols

We consider, on the basis of dimensional analysis, the use of the Knudsen number and aerosol Knudsen number in the kinetics of Brownian coagulation of aerosols. The aerosol Knudsen numberKn_p emerges naturally when one assumes that the aerosol particle motion can be described in terms of Brownian motion. Examples of dimensionless coagulation constants consistent with the use ofKn_p are also discussed.