Tsuda A, Butler J P, Fredberg J J
Department of Environmental Health, Harvard School of Public Health, Boston, Massachusetts 02115.
J Appl Physiol (1985). 1994 Jun;76(6):2510-6. doi: 10.1152/jappl.1994.76.6.2510.
We studied the effects of alveolated duct structure on deposition processes for particle diameters > or = 1 micron. For such large particles, Brownian motion is insignificant but gravity and inertial forces play an important role. A Lagrangian description of particle dynamics in an alveolated duct flow was developed, and computational analysis was performed over the physiologically relevant range. At low flow rates gravity caused deposition. Gravitational cross-streamline motion depended on the coupled effects of curvature of gas streamlines and duct orientation relative to gravity. The detailed convective flow pattern was an important factor in determining deposition. At higher flow rates, inertial impaction contributed markedly to deposition. The curved nature of streamlines again played a major role on deposition, but duct orientation had little effect. In the medium range of flow rates, both gravitational and inertial forces simultaneously influenced particle motion. Particle inertia, per se, did not cause deposition but substantially suppressed gravitational deposition. The deposition mechanism was complex; contrary to what is often assumed in past analyses, the interaction between gravitational and inertial effects could not be described in a simple additive fashion. We conclude that the structure of the alveolar duct has an important role in gravitational sedimentation and inertial impaction in the lung acinus.
我们研究了肺泡管结构对直径大于或等于1微米颗粒沉积过程的影响。对于此类大颗粒，布朗运动可忽略不计，但重力和惯性力起着重要作用。我们建立了肺泡管气流中颗粒动力学的拉格朗日描述，并在生理相关范围内进行了计算分析。在低流速下，重力导致沉积。重力横向流线运动取决于气流流线曲率和管道相对于重力的方向的耦合效应。详细的对流流动模式是决定沉积的一个重要因素。在较高流速下，惯性碰撞对沉积有显著贡献。流线的弯曲性质在沉积中再次起主要作用，但管道方向影响很小。在中等流速范围内，重力和惯性力同时影响颗粒运动。颗粒惯性本身不会导致沉积，但会显著抑制重力沉积。沉积机制很复杂；与过去分析中经常假设的情况相反，重力和惯性效应之间的相互作用不能用简单的相加方式来描述。我们得出结论，肺泡管结构在肺腺泡的重力沉降和惯性碰撞中起重要作用。
