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基于人体医学CT扫描，重建得到“鼻腔咽喉主气管一六级支气管”三维几何模型；采用大涡模拟和离散相模型的描述颗粒运动，并在拉格朗日框架下跟踪颗粒。考察了四种气载放射性微粒在典型呼吸强度下的运动和沉积。结果表明：在各工况下，气载放射性颗粒在呼吸道内运动受流道变化、缩放效应、呼吸强度和阻流面等影响较大，均呈现出明显的积聚性和沉积的高度不均匀性，易形成局部沉积热点。在4个弯曲面、2个缩放管结构区域以及支管分叉面出现大量颗粒沉积。气载放射性颗粒的沉积热点区域将导致人体组织细胞的应激反应，造成组织和器官的辐射损伤。颗粒的沉积率随粒径和呼吸强度的增加而增加，但粒径小于0．5μm后，沉积率呈相反趋势。大颗粒在呼吸道内受流道变化、呼吸强度和阻流效应等影响较大，小颗粒受布朗运动和斯坦夫升力影响更显著。

Based on the CT scanned images of the respiratory tract, a three-dimensional geometric model of realistic human upper respiratory tract including nasal cavity, pharynx, larynx, trachea and the upper six-generation bronchial was rebuilt. In order to effectively simulate the particle movement and deposition, LES model was used and the particles were tracked in the frame of Lagrange. Four kind of typical particles and three typical respiratory intensities were adopted as computational case respectively. The results of this study suggest that under most conditions, gas radioactive particles in the airway is affected by track change, spray effect, respiration intensity and blocking cross face, all showing obvious accumulation and high sedimentary inhomogeneity, tending to form ＂hot spot＂. A large number of particle depositions focus on the surface of four siphon, two spray structure and carinal ridge. Hot spots with radioactive particles will lead to the stress reaction of human body tissue cells, and cause the radiation damage of tissue and organ. The deposition rates increase with the respiration intensity, but when the size is less than 0.5μm, the deposition rate begins to decrease. Big particles are affected significantly by particle size, viscous drag and gravity, however small particles are easily affected by Brownian force and Saffman lift force.