多粒径气溶胶凝聚粒子光学特性的数值计算

Numerical Calculation of Optical Properties of Multi-Particle Size Aerosol Aggregate Particles

基于簇团-簇团凝聚(CCA)模型,利用蒙特卡罗法模拟了由不同半径球形基本粒子凝聚而成的多粒径气溶胶凝聚粒子。结合物质的电结构,将气溶胶凝聚粒子离散为一系列偶极子,利用离散偶极子近似方法,数值计算了不同波长入射情况下多粒径气溶胶凝聚粒子散射、吸收和消光效率因子等光学特征量的值,并将数值结果与等体积单一粒径气溶胶凝聚粒子和等体积球形气溶胶粒子的光学特征量进行了对比。结果表明,气溶胶粒子光学特征量的值取决于入射光的波长和气溶胶粒子的形状,并且单一粒径和多粒径气溶胶凝聚粒子的光学特性明显不同,其中多粒径凝聚粒子模型更接近实际气溶胶粒子。分析结果为理解和研究气溶胶粒子光学特性提供了一定的参考。

Based on cluster-cluster aggregation （CCA） model, Monte Carlo method is taken to simulate the multi-particle size aerosol aggregates particles which consist of spherical original particles with different radius. According to electrical structure of substance, the aerosol aggregates particles are dispersed into a series of dipoles. By using discrete dipole approximation method, the values of optical characteristic quantities are obtained, such as scattering, absorption and extinction efficiency factors of multi-particle size aerosol aggregates particles with different incident wavelengths. Numerical results are compared with the characteristic quantities of the single particle size aerosol aggregates particles and the spherical aerosol particle of equal volume. Results show that the value of optical characteristic quantities of aerosol particles depends on the wavelength of incident light and shape of aerosol particles. There is significantly difference of the optical properties between single-particle size aerosol aggregates particles and multi-particle ones. The multi-particle size aerosol aggregates particles model is much closer to real aerosol particles. The findings provide a certain reference for comprehensive understanding and researching on the optical properties of aerosol particles.