In this project simulation of fluid flow and tracking particles in the human's lung alveolar duct have been performed using Computational Fluid Dynamic (CFD). For this purpose, laminar fluid flow in the human alveolar duct has been performed using deforming zones ability of dynamic mesh method. Despite of the most of simulations, fluid flow simulation has been done absolutely time dependently and inlet and outlets of solution domain, have been applied automatically from domain boundaries motion. The simulated cases can be divided into three groups. In the first group particle tracking and determination deposition efficiency of cigarette smokes is done. In the second group tracking and determination deposition efficiency of microorganisms like Influenza Viruses have been performed. Finally in the third group, investigating effects of special zone of human’s lung deforming zone on the lung performance has been carried out. Time dependent particle tracking has been done accurately, using fluid flow simulation results. For this purpose, Brownian motion of sub-micron particles has been considered using polar type of random number generators. Final results show that deposition efficiency for sub-micron particles has a reverse trend with particle size. Efficiency will decrease after increasing particle size. The main reason for this is that randomized Brownian motion of air molecules will affect particles more, if the particle size is small. Simulations results of micro-organism motion in human alveolar zone for two sizes of particles (30 nanometer and 0.2 micrometer) demonstrates higher values of deposition for finer micro-organisms compared with larger ones. Finally simulation results for malfunction of some parts have been done for two different conditions of alveolar duct malfunction. The results show that in both cases deposition efficiency will decrease. This phenomenon is clearer for coarser particles in the second case. Key Words Lung, Lump model, Resistance, Inductance, Capacitance, Bifurcation, Electric circuit
