Mathematical Modeling of the Dynamics and Thermodynamics of Multicomponent Atmospheric Aerosols

Citation

Pilinis, Christodoulos (1988) Mathematical Modeling of the Dynamics and Thermodynamics of Multicomponent Atmospheric Aerosols. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/t5w6-2r52. https://resolver.caltech.edu/CaltechETD:etd-11072007-140642

Abstract

Atmospheric aerosols consist of particles with sizes between 0.01 and 10µm. These particles, when occurring in urban areas, consist, in general, of aqueous solutions of sulfate, nitrate, ammonium, chloride, sodium and other ionic species, as well as of primary and secondary organics.

This thesis attempts to describe the evolution and fate of atmospheric aerosol particles. The size-composition distribution of atmospheric aerosols is governed by a combination of kinetics and thermodynamics, which, because of their complexity, can be analyzed only with computer simulations. At first, a solution of the General Dynamic Equation in the case of small coagulation, using perturbation techniques, is developed.

In subsequent work, a comprehensive size-sectionalized trajectory aerosol model was developed for simulating the evolution of a multicomponent aerosol size-composition distribution through homogeneous heteromolecular nucleation, condensational growth, coagulation and deposition. The model was employed along a trajectory from Anaheim to Rubidoux, California.

In the process of analyzing this model it became apparent that a detailed treatment of the thermodynamics of the sodium/ sulfate/ nitrate/ ammonium/ chloride/ water system is very important in aerosol predictions. Thus, an equilibrium model for this system that takes into account differences in the composition among particles of different sizes was developed and tested.

Finally, the same theory was used in a Eulerian framework, thus producing a three-dimensional Eulerian Urban Gas-Aerosol Model, which was used to predict the aerosol concentration and size distribution throughout the Los Angeles Basin on August 30, 1982. Its prediction is compared with measured values and a statistical evaluation study is presented.

Thesis Files