COLLISION AND COAGULATION IN THE INFINITE-STOKES-NUMBER REGIME

This paper presents a theoretical description of collision and coagula tion in the infinite-Stokes-number limit where particle motions are on ly weakly correlated with the fluid. A methodology for predicting the collision frequency and the particle mean energy is developed based on the assumption of a Maxwellian velocity distribution. The prediction of particle energies is crucial to the theory because it is shown that coagulation inherently dissipates a fraction of the particle kinetic energy; thus, each subsequent generation of particles has progressivel y lower energies. Prediction of the increasingly nonequilibrium system requires an energy balance for each particle category in addition to the standard population equation. The results of the theory compare re asonably well with direct numerical simulations, although it is pointe d out that minor discrepancies do arise with coagulation due to the ne glect of particle mixing in the theory. A future study will address th is limitation. (C) 1998 American Association for Aerosol Research.