Coagulation kernel of particles in a turbulent gas flow

On the base of modern probability density functions approach turbulent coagulation of particles in gravitational field is investigated. Spectral presentation of second velocity moments of gas phase is used for calculation of intensity of particles relative chaotic motion. Closed diffusion equation for two-particle distribution in space is obtained. Boundary condition taking into account coefficients of new particle formation and momentum restitution during two particles collision is found. Formula for calculation of turbulent coagulation kernel of particles in gravity field is gain. Influence of cloud turbulence and turbulence in a pipe flow on intensity of droplets coagulation is studied. Strong effects of relative turbulent diffusion between droplets, droplets inertia and droplets gravitational settling on intensity of coagulation are found out. Connection between internal structure of turbulence type and coagulation rate is illustrated. Obtained results are right for polydisperse additions in turbulent flows. (c) 2006 Elsevier Ltd. All rights reserved.