One-order closed model of fluctuating particle coagulation term in the Reynolds averaged general dynamic equation for nanoparticles

The effect of fluctuating coagulation on particle distribution in multiphase turbulence of nanoparticles was studied based on the Reynolds averaged equation of turbulence flow and the general dynamic equation of particles. A one-order closed model was proposed to relate the fluctuating coagulation term to the average particle size distribution function for closing the particle equation. The proposed model and equations were applied to a turbulent jet flow using the k-ε turbulent model and the Taylor-series expansion moment method. The results showed that there is a difference in the values of particle number density M₀, geometric average diameter d_pg and geometric standard deviation σ_g of particle diameter with and without considering fluctuating coagulation. Larger Damkohler number leads to smaller M₀, higher particle polydispersity M₂, larger d_pg and σ_g. Along the x direction of the flow, M₀ decreases, while M₂, d_pg and σ_g increase. From the centerline to the outer edge of the jet, M₀, M₂ and d_pg decrease, while σ_g increases first and then decreases. Finally, the further research that can be carried out has been proposed.