The purpose of this paper is to investigate aerosol evolution in a planar mixing layer from a Lagrangian point of view. After using Monte Carlo (MC) method to simulate the evolution of aerosol dynamics along particles trajectories, the particles size distributions are obtained, which are unavailable in mostly used methods of moments.
Nucleation and growth of dibutyl phthalate (DBP) particles are simulated using the quadrature method of moments in a planar mixing layer, where a fast hot stream with DBP vapor is mixing with a slow cool stream without vapor. Trajectories of aerosol particles are recorded. MC method is used to simulate the aerosol evolution along trajectories.
Investigation on aerosol evolution along the trajectories prompts to classify these trajectories into three groups: first, trajectories away from the active nucleation zone; second, trajectories starting from the active nucleation zone; and third, trajectories crossing over the active nucleation zone. Particle size distributions (psds) along selected representative trajectories are investigated. The psd evolution exhibits interesting behavior due to the synthetic effects of nucleation and condensation. Condensation growth tends to narrow down the psd, and form a sharp front on the side of big particle size. Nucleation is able to broaden the psd through generating the smallest particles. The duration and strength of nucleation have significant effect on the shape of psd.
As far as the authors knowledge, it is the first simulation of aerosol evolution that takes a Lagrangian point of view, and uses MC simulation along particles trajectories to provide the particles size distribution.
The author KZ would like to thank the help from F. Bisetti and A. Attili in KAUST. The program codes for the Lagrangian trajectories are implemented by A. Attili. The work is supported by the National Natural Science Foundation of China (No. 11402179, 51404176).
Zhou, K. and He, Z. (2014), "Monte Carlo simulation of aerosol evolution in a planar mixing layer", International Journal of Numerical Methods for Heat & Fluid Flow, Vol. 24 No. 8, pp. 1769-1781. https://doi.org/10.1108/HFF-04-2013-0123
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