气溶胶凝聚粒子散射特性的数值计算

利用Cluster-cluster aggregation (CCA)模型，模拟了由相同数目球形原始微粒凝聚而成的四种随机取向气溶胶凝聚粒子．根据物质的电结构，将气溶胶凝聚粒子离散为一系列偶极子，结合离散偶极子近似方法，在获得每一个偶极子的电偶极矩之后，数值计算了气溶胶凝聚粒子散射强度的角分布，并分析了散射强度随入射光入射角度和气溶胶凝聚粒子尺寸参数变化的规律．结果显示：当散射角较小时，气溶胶凝聚粒子取向和入射光的入射角度对散射强度影响不大，当散射角增大时，散射强度则明显依赖于气溶胶凝聚粒子取向和入射光的入射角度；对于不同尺寸参数的气溶胶凝聚粒子，在同一角度入射情况下，随尺寸参数的增加，气溶胶凝聚粒子的散射主要集中于前向散射．

Numerical calculation of scattering characteristics for aerosol aggregation particles

Cluster-cluster aggregation (CCA) model is used to simulate four kinds of randomly oriented aerosol aggregation particles which consist of the same number of spherical original particles. According to the electrical structure of substance, the aerosol aggregation particles are dispersed into a series of dipoles, and then by combining with the discrete dipole approximation method and after obtaining the electric dipole moment of each dipole, the angular distribution of scattering intensity of aerosol aggregation particles is given, and the variations of scattering intensity with incident angle of incident light and size parameter of aerosol aggregation particles are analyzed. The results show that the orientation of aerosol aggregation particles and incident angle of incident light have little effect on scattering intensity when the scattering angle becomes smaller; while with the scattering angle being bigger, the scattering intensity is significantly dependent on the orientation of aerosol aggregation particles and the incident angle of incident light. For the aerosol aggregation particles with different size parameters and under the same incident angle, the scattering of aerosol aggregation particles is mainly concentrated in the forward scattering with the increasing size parameter.