Modeling of Aerosol Transport in Alveolated Airways

这项研究的长期目标是更好地了解吸入颗粒在人体肺部的命运。近年来，随着越来越多的证据将空气污染与死亡率联系起来，暴露于颗粒物（PM）一直是一个主要问题。更好地了解肺中的气溶胶沉积（DE）也可能有利于吸入药物治疗等应用。数学模型经常被用来帮助解释实验研究，并在没有实验数据的情况下做出预测。在对称和不对称两种二维模式下，气溶胶在人肺肺泡区的传输将被模拟，其中0.5 ~ 5 μ m粒子主要是由于重力沉降。结构相对于重力矢量的方向是影响DE模式的主要因素。CM导致吸入的颗粒在通过肺部的运输过程中不可逆地转移到常驻空气中。由于这种转移，一些没有沉积在气道壁上的颗粒在正常呼气结束时仍悬浮在远端气道中，无法排出肺部。这些微粒在下一次呼吸时深入肺部并最终沉积。肺泡区的速度分布预计是影响CM的主要因素。模拟将使我们能够分离出它们的影响，并确定它们对总体CM的贡献。最后模拟了拉伸和折叠引起的额外CM对人肺颗粒肺泡DE的影响。拉伸和折叠指的是由于肺部流动的不可逆性，空气流线自己折叠起来，加强混合的过程。这项研究的结果可能提供了一种机制，通过这种机制，即使看似适度的PM暴露也会导致或加剧肺部疾病。这些结果也将有助于更好地设计吸入治疗药物的空间靶向。

The long-term objective of this study is to better understand the fate of inhaled particles in the human lung. Exposure to particulate matter (PM) has been a major concern in the recent years as more evidence links air pollution and mortality. A better understanding of aerosol deposition (DE) in the lung may also be beneficial in applications such as inhalation drug therapy. Mathematical models are often used to help interpret the experimental studies and to make predictions for cases where experimental data are not available. Aerosol transport in both symmetrical and asymmetrical two-dimensional models of the alveolar zone of the human lung will be simulated ro 0.5 to 5 mum particles is mainly due to gravitational sedimentation. The orientation of the structure with respect to the gravity vector is a major factor affecting DE patterns. CM causes inhaled particles to be irreversibly transferred to the resident air during their transport through the lung. Because of this transfer, some particles that do not deposit on the airway walls remain in suspension in the distal airways at the end of a normal expiration and fail to exit the lung. These particles then penetrate deeper in the lung during the next breath and eventually deposit. Velocity profiles in the alveolar region of the lung are expected to be a major factor that affects CM. The simulations will allow us to isolate their effect and to determine their contribution to overall CM. Finally the effects of extra CM caused by stretch and fold on the alveolar DE of particles in the human lung will be simulated. Stretch and fold refers to the process where, because of non-reversibility of flow in the lung, air streamlines become folded back on themselves, enhancing mixing. The results of this study may provide a link to the mechanisms by which even seemingly modest exposure to PM can cause or exacerbate lung disease. The results will also help to better design spatial targeting of drugs administered by inhalation therapy.