COAGULATION OF SMOKE AEROSOL IN A BUOYANT PLUME

The mechanism of particulate coagulation in a turbulent plume is studied by combining the Morton-Taylor-Turner theory of turbulent buoyant plumes with the present authors' earlier analysis of coagulation in a homogeneous system. The conservation of fluid mass, particulate matter, momentum, and energy leads to a set of differential equations for horizontal averages of hydrodynamic quantities. These relations are combined with the horizontally averaged coagulation equation to yield an equation which is transformed to be exactly equivalent to the problem of coagulation in a homogeneous medium. The effective time scale is a known function of the vertical plume height which is determined by solving the plume hydrodynamic equations. This permits the coagulation process in a homogeneous system to be quantitatively related to that in a buoyant plume. Sample calculations are performed to illustrate the effects of the initial number and mass concentrations of the particulate, rate of heat release, initial plume momentum, and atmospheric stratification on the aging process. Results indicate that the coagulation process can be frozen" if the entrainment of uncontaminated air into the plume sufficiently dilutes the particulate concentration. Calculations of the number flux and the particle size D32 as a function of plume height are included. © 1979."