Low H T, Chew Y T, Zhou C W
Department of Mechanical & Production Engineering, National University of Singapore, Singapore.
J Biomech Eng. 1997 Aug;119(3):298-308. doi: 10.1115/1.2796094.
This paper considers the effects of non-Newtonian lining-fluid viscosity, particularly shear thinning and yield stress, on the reopening of the airways. The airway was simulated by a very thin, circular polyethylene tube, which collapsed into a ribbon-like configuration. The non-Newtonian fluid viscosity was described by the power-law and Herschel-Buckley models. The speed of airway opening was determined under various opening pressures. These results were collapsed into dimensionless pressure-velocity relationships, based on an assumed shear rate gamma = U/(0.5 H), where U and H are the opening velocity and fluid film thickness, respectively. It was found that yield stress, like surface tension, increases the yield pressure and opening time. However, shear thinning reduces the opening time. An increased film thickness of the non-Newtonian lining fluid generally impedes airway reopening; a higher pressure is needed to initiate the airway reopening and a longer time is required to complete the opening process.
本文研究了非牛顿衬里流体粘度，特别是剪切变稀和屈服应力对气道重新开放的影响。气道由非常细的圆形聚乙烯管模拟，该管会塌陷成带状结构。非牛顿流体粘度由幂律模型和赫谢尔-巴克利模型描述。在各种开放压力下确定气道开放速度。基于假定的剪切速率γ = U/(0.5H)（其中U和H分别为开放速度和液膜厚度），将这些结果归纳为无量纲压力-速度关系。研究发现，屈服应力与表面张力一样，会增加屈服压力和开放时间。然而，剪切变稀会缩短开放时间。非牛顿衬里流体膜厚度增加通常会阻碍气道重新开放；启动气道重新开放需要更高的压力，并且完成开放过程需要更长的时间。
