CHAOTIC MIXING OF AEROSOL IN RHYTHMICALLY EXPANDING LUNG

气溶胶动力学的基本知识对于理解 许多重要的生理过程，如环境暴露， 致病颗粒，或治疗和诊断应用 气溶胶释放物质。 我们的主要目标是了解气溶胶 肺外周的行为。 现有的数学 气溶胶输送和沉积模型考虑了粘性流 可逆的，因此，理论上排除了 腺泡区域中的对流（流动诱导）混合。 如违反本 理论和实验数据表明， 腺泡 最近发现，粘性流可以是不可逆的， 该流动表现出混乱的结构（Reynino，et al.，自然， 333（6172），419 -425，1988）开辟了流体力学的新途径， 描述流体的混沌行为作为混合的重要因素。 研究腺泡管结构特征的影响， 特别是时间依赖的几何膨胀的影响， 肺泡壁的流动行为，我们观察到的现象 混沌流的特征。根据这些观察，我们 假设复杂混沌流可以有节奏地发生在 正常呼吸时肺泡管结构的伸缩 并且它可以导致强烈的流动诱导（混沌）混合。 我们提出 用一系列数学分析来验证这个假设 物理肺泡中的拉格朗日粒子跟踪和流动显示 模型和动物肺。 我们将量化混合的程度， 计算示踪粒子的熵的时间演化。 这 新的概念导致了一个完全不同的和可量化的图片， 以前使用的传播和分散的想法。 我们认为 这项研究的结果将使我们对气溶胶有新的认识。 动力学，并将帮助我们了解重要的生理 流程.

Basic knowledge of aerosol kinetics is essential for the understanding of many important physiological processes, such as environmental exposure to pathogenic particles, or therapeutic and diagnostic application of aerosol delivered substances. Our major goal is to understand aerosol behavior in the lung periphery. The currently existing mathematical models of aerosol transport and deposition consider the viscous flow reversible and, therefore, theoretically exclude the possibility of convective (flow-induced) mixing in the acinar region. Contrary to these theories, experimental data suggest appreciable convective mixing in the acinus. The recent discovery that viscous flow can be irreversible if the flow exhibits a chaotic structure (Ottino, et al., Nature, 333(6172),419-425, 1988) has opened up a new avenue in fluid mechanics, describing chaotic behavior of fluids as an important factor in mixing. Studying the influence of structural characteristics of the acinar duct, in particular the effects of time-dependent geometric expansion of alveolar walls on flow behavior, we have observed phenomena characteristic of chaotic flow. Based on these observations we hypothesize that complex chaotic flow can occur in the rhythmically expanding-contracting alveolated duct structure during normal breathing and it can result in strong flow-induced (chaotic) mixing. We propose to test this hypothesis with a combination of mathematical analyses - Lagrangian particle tracking and flow visualization in physical alveolus models and with animal lungs. We will quantify the extent of mixing by computing the time evolution of the entropy of tracer particles. This new concept leads to a totally different and quantifiable picture of the previously used ideas of spreading and dispersion. We believe that the results of this proposed study would give us new insight into aerosol kinetics and would help us in understanding important physiological processes.