Analysis of Brownian coagulation in the spatial mixing layer based on average kernel coupled with iterative direct numerical simulation framework

Abstract: This study investigates the evolution of nanoparticle populations undergoing Brownian coagulation in a spatial mixing layer. The dynamics of particle size distribution and number concentration are analyzed using a coupled Eulerian approach that combines fluid dynamics with aerosol dynamics. The mixing layer serves as a fundamental flow configuration to understand particle-vortex interactions and their effect on coagulation rates. Results demonstrate that the shear-induced spatial mixing significantly influences the spatial distribution of nanoparticles and their subsequent coagulation behavior. The enhanced mixing in the shear layer leads to locally increased particle collision frequencies, accelerating the coagulation process compared to laminar conditions. The study reveals that the evolution of the particle size distribution is strongly dependent on both the local vorticity intensity and the initial particle concentration gradients across the mixing layer.