Collision and Coagulation in the Infinite-Stokes-Number Regime

ABSTRACT

This paper presents a theoretical description of collision and coagulation in the infinite-Stokes-number limit where particle motions are only 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 progressively 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 reasonably well with direct numerical simulations, although it is pointed out that minor discrepancies do arise with coagulation due to the neglect of particle mixing in the theory. A future study will address this limitation.