1 Department of Mechanical and Nuclear Engineering, Virginia Commonwealth University, Richmond, Virginia.
2 Department of Pharmaceutics, and Virginia Commonwealth University, Richmond, Virginia.
J Aerosol Med Pulm Drug Deliv. 2019 Jun;32(3):132-148. doi: 10.1089/jamp.2018.1490. Epub 2018 Dec 15.
Computational fluid dynamics (CFD) provides a powerful tool for developing new high-efficiency aerosol delivery strategies, such as nose-to-lung (N2L) aerosol administration to infants and children using correctly sized aerosols. The objective of this study was to establish numerically efficient CFD solution methods and guidelines for simulating N2L aerosol administration to an infant based on comparisons with concurrent experiments. N2L administration of a micrometer-sized aerosol (mass median aerodynamic diameter [MMAD] = 1.4 μm) was evaluated using concurrent CFD simulations and experiments. Aerosol transport and deposition was assessed in a new nasal airway geometry of a 6-month-old infant with a streamlined nasal cannula interface, which was constructed as a CFD mesh and three-dimensionally printed to form an identical physical prototype. CFD meshes explored were a conventional tetrahedral approach with near-wall (NW) prism elements and a new polyhedral mesh style with an equally refined NW layer. The presence of turbulence in the model was evaluated using a highly efficient low-Reynolds number (LRN) k-ω turbulence model, with previously established NW corrections that accounted for anisotropic wall-normal turbulence as well as improved NW velocity interpolations and hydrodynamic particle damping. Use of the new polyhedral mesh was found to improve numerical efficiency by providing more rapid convergence and requiring fewer control volumes. Turbulent flow was found in the nasal geometry, generated by the inlet jets from the nasal cannula interface. However, due to the small particle size, turbulent dispersion was shown to have little effect on deposition. Good agreement was established between the CFD predictions using the numerically efficient LRN k-ω model with appropriate NW corrections and deposition data. Aerosol transmission efficiencies through the delivery tube, nasal cannula, and infant nasal model, based on experimental and CFD predictions, were 93.0% and 91.5%, respectively. A numerically efficient CFD approach was established to develop transnasal aerosol administration to infants and children. Small particle aerosols with aerodynamic diameters of ∼1.5 μm were confirmed to have low inertial depositional loss, and have low deposition from turbulent dispersion, making them ideal for high-efficiency lung delivery through an infant nasal cannula interface.
计算流体动力学（CFD）为开发新的高效气溶胶输送策略提供了强大的工具，例如使用正确尺寸的气溶胶对婴儿和儿童进行鼻内（N2L）气溶胶给药。本研究的目的是建立数值高效的 CFD 求解方法和指南，以基于与同期实验的比较来模拟对婴儿的 N2L 气溶胶给药。使用同期 CFD 模拟和实验评估了亚微米大小的气溶胶（质量中值空气动力学直径[MMAD]=1.4μm）的 N2L 给药。在具有流线型鼻插管接口的 6 个月大婴儿的新鼻气道几何形状中评估了气溶胶的输送和沉积，该接口被构造成 CFD 网格并通过三维打印形成相同的物理原型。探索的 CFD 网格包括具有近壁（NW）棱柱元素的传统四面体方法和具有同样精细 NW 层的新多面体网格样式。通过使用高效的低雷诺数（LRN）k-ω湍流模型评估模型中的湍流，该模型采用了先前建立的 NW 校正，该校正考虑了各向异性壁法向湍流以及改进的 NW 速度插值和流体动力颗粒阻尼。发现使用新的多面体网格可以提高数值效率，因为它可以提供更快的收敛速度并需要更少的控制体积。在鼻几何形状中发现了由鼻插管接口的入口射流产生的湍流。然而，由于颗粒尺寸较小，湍流分散对沉积的影响很小。通过使用具有适当 NW 校正的数值高效 LRN k-ω模型与沉积数据之间建立了良好的一致性。基于实验和 CFD 预测，输送管、鼻插管和婴儿鼻模型中的气溶胶传输效率分别为 93.0%和 91.5%。建立了一种数值高效的 CFD 方法来开发对婴儿和儿童的经鼻气溶胶给药。具有约 1.5μm 的空气动力学直径的小颗粒气溶胶被证实具有低惯性沉积损失，并且由于湍流分散而具有低沉积，这使它们成为通过婴儿鼻插管接口进行高效肺部输送的理想选择。
