Department of Biomedical Engineering, University of Massachusetts, 1 University Ave., Lowell, MA 01854, USA.
Department of Aerospace, Industrial, and Mechanical Engineering, California Baptist University, 8432 Magnolia Ave, Riverside, CA 92504, USA.
Math Biosci Eng. 2022 Aug 1;19(11):10915-10940. doi: 10.3934/mbe.2022510.
Previous numerical studies of pulmonary drug delivery using metered-dose inhalers (MDIs) often neglected the momentum transfer from droplets to fluid. However, Kolmogorov length scales in MDI flows can be comparable to the droplet sizes in the orifice vicinity, and their interactions can modify the spray behaviors. This study aimed to evaluate the two-way coupling effects on spray plume evolutions compared to one-way coupling. The influences from the mass loading, droplet size, and inhaler type were also examined. Large-eddy simulation and Lagrangian approach were used to simulate the flow and droplet motions. Two-way coupled predictions appeared to provide significantly improved predictions of the aerosol behaviors close to the Ventolin orifice than one-way coupling. Increasing the applied MDI dose mass altered both the fluid and aerosol dynamics, notably bending the spray plume downward when applying a dose ten times larger. The droplet size played a key role in spray dynamics, with the plume being suppressed for 2-µm aerosols and enhanced for 20-µm aerosols. The Kolmogorov length scale ratio dp/η correlated well with the observed difference in spray plumes, with suppressed plumes when dp/η < 0.1 and enhanced plumes when dp/η > 0.1. For the three inhalers considered (Ventolin, ProAir, and Qvar), significant differences were predicted using two-way and one-way coupling despite the level and manifestation of these differences varied. Two-way coupling effects were significant for MDI sprays and should be considered in future numerical studies.
先前使用计量吸入器 (MDI) 进行肺部药物输送的数值研究通常忽略了液滴向流体的动量传递。然而，MDI 流中的柯尔莫哥洛夫长度尺度可以与喷口附近的液滴尺寸相当，它们的相互作用可以改变喷雾行为。本研究旨在评估与单向耦合相比，双向耦合对喷雾羽流演化的影响。还研究了质量负荷、液滴尺寸和吸入器类型的影响。大涡模拟和拉格朗日方法用于模拟流动和液滴运动。与单向耦合相比，双向耦合预测似乎显著改善了靠近 Ventolin 喷口的气溶胶行为的预测。增加应用的 MDI 剂量质量会改变流体和气溶胶动力学，特别是当应用十倍于正常剂量时，会使喷雾羽流向下弯曲。液滴尺寸在喷雾动力学中起着关键作用，对于 2 µm 的气溶胶，羽流被抑制，对于 20 µm 的气溶胶，羽流增强。dp/η 与观察到的喷雾羽流差异之间存在很好的相关性，当 dp/η < 0.1 时，羽流被抑制，当 dp/η > 0.1 时，羽流增强。对于考虑的三种吸入器（Ventolin、ProAir 和 Qvar），尽管这些差异的水平和表现不同，但使用双向和单向耦合都预测到了显著差异。对于 MDI 喷雾，双向耦合效应非常显著，应在未来的数值研究中考虑。
