SIMULATION OF BROWNIAN COAGULATION IN THE PRESENCE OF VAN-DER-WAALS FORCES AND VISCOUS INTERACTIONS

Coagulation of aerosol particles in the size range of 0.001-10 mum in particle aerodynamic diameter is simulated by using a model based on a sectional representation of the aerosol size distribution. The influe nce of van der Waals forces and viscous interactions are both incorpor ated, and this interaction enhanced coagulation is compared with coagu lation resulting from pure Brownian movement. The interparticle van de r Waals potential applied in calculations is based partially on Hamake r's theory and partially on the limiting approximations to the equatio ns of Langbein. Viscous interactions are incorporated by using a corre cted form of the particle binary diffusion coefficient. As expected, c oagulation between ultrafine particles was clearly enhanced due to the interactions. No essential differences between Brownian and interacti on influenced coagulation was to be seen above 0.05 mum of particle di ameter or between particles located in separate size modes.