屏气状况下重力方向对肺腺泡内颗粒物沉积特性影响的数值模拟（英文）

Numerical Simulation of the Effect of Gravitational Direction on Particle Deposition in Pulmonary Acinus under the Condition of Breath Holding

本文通过现有的肺腺泡区的二维几何模型,对由吸气转入屏气后肺腺泡区域的颗粒物沉积特性以及屏气状况下-y重力方向和+x重力方向对颗粒在肺腺泡内沉积的影响进行模拟.结果表明:在屏气情况下,粒径大(1μm,2μm,3μm)的颗粒运动受重力主导,粒径小(0.01μm)的颗粒运动受布朗力主导,它们的沉积率随屏气时间的增加而快速增加,很快达到稳定;而中间粒径(0.1μm,0.5μm)的颗粒运动受重力和布朗力作用相当,沉积缓慢.不同重力方向会影响颗粒沉积到不同的位置,所以重力方向对肺腺泡整体沉积率几乎没有影响,但能影响肺腺泡特定区域的沉积率,与-y重力方向相比,+x重力方向能增加某些特定区域的沉积率.本文二维肺腺泡内颗粒物沉积的特性研究,将为肺部物质输运以及呼吸系统吸入疗法的深入研究提供可靠的理论依据.

A two-dimensional CFD simulation is conducted to study the effect of the gravitational direct ion on particle deposition in pulmonary acinus when the breath is held for a short time. The results show that for the large particles （particle diameters of 1 μm, 2 μm, and 3 μm） , gravity is the dominant force, and for the small particles （particle diameter of 0. 01μm） , the Brownian force is significant. Under the ac-tion of either force, the deposition time of particles is short and an equilibrium state can be reached quickly. However, for the medium-sized particles （particle diameters of 0. 1 ｜xm and 0. 5 ｜xm） , the dep-osition time of particles is elongated because both gravity and Brownian force become weak. Meanwhile, the directions of applied gravity relative to the pulmonary acinus affect the deposition zone of these part i-cles. Therefore, the gravitational direct ion has no effect on the total deposition fraction of the pulmonary acinus, but can change the local deposition fract ion. Applying gravity along the ＋x d irect io n would in -crease the local deposition fract ion in some specific generations in comparison with the situation along the -y direct ion. The present study can provide a reliable theoretical basis for further studies on pulmonary mass transport and inhalation therapy.