Laminar-to-turbulent fluid-particle flows in a human airway model
Laminar-to-turbulent fluid-particle flows in a human airway model
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DOI：
10.1016/s0301-9322(02)00131-3
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发表时间：
2003-02-01
影响因子：
3.8
通讯作者：
Zhang, Z
中科院分区：
文献类型：
--
作者：
Kleinstreuer, C;Zhang, Z
在许多生物医学和工业应用中，根据进口流速和管的几何形状，具有局部收缩的弯曲管中的气固两相流场可能是层流、过渡流和/或湍流流。假设稳定的不可压缩气流和非相互作用的球形微米颗粒，使用带有用户提供的预处理和后处理程序的商业软件解决了人体气道模型的层流到湍流悬浮流动问题。用低雷诺数k-omega湍流模型捕获了所有流态（500 < Re-local < 10(4)）。考虑不同的稳态吸气流量（15小于等于Q小于等于60 l/min）和Stokes数，三维模拟结果表明：(i)当吸气流量从低水平呼吸（Q(in) = 15l /min）转变为高水平呼吸（Q(in) = 60 l/min）时，可以明显观察到喉部收缩后湍流的发生。随着向湍流过渡的发生，气管内流动再附着长度变短，轴向速度剖面变钝，二次流衰减更快。（ii）在较低吸气流量下（Q(in) = 15 l/min），颗粒很好地遵循气流与颗粒运动的基本关系；然而，粒子的运动似乎是随机和分散的，即在高吸气流量（Q(in) = 60l /min）的情况下，受流量波动的影响。（iii）湍流可以在一定程度上增强喉部附近气管内的颗粒沉积，但在相对高流速（Q(in) = 30和60l /min）下，湍流弥散更容易影响整个气道内较小颗粒（如St < 0.06）的沉积。然而，与单独的湍流分散相比，颗粒大小和吸入流速（即斯托克斯数）仍然是影响颗粒沉积的主要因素。所概述的方法可以很容易地应用于复杂管状系统中发生流型变化的其他两相流。2003爱思唯尔科学有限公司版权所有。
As in many biomedical and industrial applications, gas-solid two-phase flow fields in a curved tube with local area constrictions may be laminar, transitional and/or turbulent depending upon the inlet flow rate and tube geometry. Assuming steady incompressible air flow and non-interacting spherical micron-particles, the laminar-to-turbulent suspension flow problem was solved for a human airway model using a commercial software with user-supplied pre- and post-processing programs. All flow regimes (500 < Re-local < 10(4)) were captured with an low-Reynolds-number k-omega turbulence model. Considering different steady inspiratory flow rates (15less than or equal toQless than or equal to60 l/min) and Stokes numbers, the three-dimensional simulation results show the following:(i) The onset of turbulence after the constriction in the larynx can be clearly observed when the inspiratory flow rate changes from low-level breathing (Q(in) = 15 l/min) to high-level breathing (Q(in) = 60 l/ min). The flow reattachment length in the trachea becomes shorter, the axial velocity profile becomes more blunt, and the secondary flow decays faster with the occurrence of transition to turbulence.(ii) Particles follow the basic relationship between airflow and particle motion very well at the lower inspiratory flow rate (Q(in) = 15 l/min); however, particle motion seems to be random and disperse, i.e., influenced by flow fluctuations in case of high inspiratory flow (Q(in) = 60 l/min).(iii) Turbulence can enhance particle deposition in the trachea near the larynx to some extent, but it is more likely to affect the deposition of smaller particles (say, St < 0.06) throughout the airway at relatively high flow rates (Q(in) = 30 and 60 l/min) due to turbulent dispersion. However, the particle size and inhalation flow rate (i.e., Stokes number) are still the main factors influencing particle deposition when compared with turbulent dispersion alone.The methodology outlined can be readily applied to other two-phase flows undergoing changing flow regimes in complex tubular systems. (C) 2003 Elsevier Science Ltd. All rights reserved.