The bimodal Taylor expansion method of moments (B-TEMOM) model scheme was developed to simulate the formation and evolution of vehicle exhaust particles. Two independent types of log-normal particle size distributions were selected in the B-TEMOM model scheme, comprising large and small particles to represent background (i.e., the surrounding environment) and vehicle exhaust particles, respectively. Concentration distributions of exhaust and background particles derived using this model scheme were verified against results from a moving sectional method and the bimodal quadrature method of moments, showing excellent agreement. The effects of vehicle tailpipe exit conditions (e.g., exhaust particle concentrations and velocity), sulfur content, and relative humidity on the evolution of particles were investigated numerically. Both two-dimensional and three-dimensional numerical simulations showed that tailpipe exit velocity and relative humidity did not greatly affect the steady-state concentrations or the diameters of particles in urban atmospheres. Although an increase in sulfur content had little effect on the particle concentration, it led to background particles with larger geometric average diameter entering the environment. This coupled CFD-B-TEMOM numerical model provides a simple but accurate and efficient method for studying bimodal aerosol dynamics.

开发了双峰泰勒矩矩展开法（B-TEMOM）模型方案，以模拟车辆排气颗粒的形成和演化。在B-TEMOM模型方案中选择了两种独立的对数正态粒径分布，分别包括代表背景（即周围环境）的大颗粒和小颗粒和车辆尾气颗粒。利用动截面法和双峰矩矩法的结果验证了使用该模型方案得出的排气和背景颗粒的浓度分布，显示出极好的一致性。数值研究了车辆排气管出口条件（例如，排气颗粒浓度和速度），硫含量和相对湿度对颗粒演变的影响。二维和三维数值模拟均表明，排气管的出口速度和相对湿度对城市大气中的稳态浓度或颗粒直径没有太大影响。尽管硫含量的增加对颗粒浓度几乎没有影响，但它导致具有较大几何平均直径的背景颗粒进入环境。这种耦合的CFD-B-TEMOM数值模型为研究双峰气溶胶动力学提供了一种简单但准确有效的方法。它导致具有较大几何平均直径的背景粒子进入环境。这种耦合的CFD-B-TEMOM数值模型为研究双峰气溶胶动力学提供了一种简单但准确有效的方法。它导致具有较大几何平均直径的背景粒子进入环境。这种耦合的CFD-B-TEMOM数值模型为研究双峰气溶胶动力学提供了一种简单但准确有效的方法。