Fazla Bartu, Erken Oguzhan, Izbassarov Daulet, Romanò Francesco, Grotberg James B, Muradoglu Metin
Department of Mechanical Engineering, Koc University, Istanbul, 34450, Turkey.
School of Engineering, Institute for Infrastructure and Environment, The University of Edinburgh, Edinburgh, United Kingdom.
J Nonnewton Fluid Mech. 2024 Aug;330. doi: 10.1016/j.jnnfm.2024.105281. Epub 2024 Jun 24.
The formation of a liquid plug inside a human airway, known as airway closure, is computationally studied by considering the elastoviscoplastic (EVP) properties of the pulmonary mucus covering the airway walls for a range of liquid film thicknesses and Laplace numbers. The airway is modeled as a rigid tube lined with a single layer of an EVP liquid. The Saramito-Herschel-Bulkley (Saramito-HB) model is coupled with an Isotropic Kinematic Hardening model (Saramito-HB-IKH) to allow energy dissipation at low strain rates. The rheological model is fitted to the experimental data under healthy and cystic fibrosis (CF) conditions. Yielded/unyielded regions and stresses on the airway wall are examined throughout the closure process. Yielding is found to begin near the closure in the Saramito-HB model, whereas it occurs noticeably earlier in the Saramito-HB-IKH model. The kinematic hardening is seen to have a notable effect on the closure time, especially for the CF case, with the effect being more pronounced at low Laplace numbers and initial film thicknesses. Finally, standalone effects of rheological properties on wall stresses are examined considering their physiological values as baseline.
通过考虑覆盖气道壁的肺黏液在一系列液膜厚度和拉普拉斯数下的弹黏塑性（EVP）特性，对人体气道内液体栓塞的形成（即气道闭合）进行了计算研究。气道被建模为内衬单层EVP液体的刚性管道。将萨拉米托-赫谢尔-巴克利（Saramito-HB）模型与各向同性运动硬化模型（Saramito-HB-IKH）相结合，以允许在低应变率下耗散能量。流变模型拟合了健康和囊性纤维化（CF）条件下的实验数据。在整个闭合过程中检查气道壁上的屈服/未屈服区域和应力。发现在Saramito-HB模型中，屈服在闭合附近开始，而在Saramito-HB-IKH模型中，屈服明显更早发生。运动硬化对闭合时间有显著影响，尤其是对于CF情况，在低拉普拉斯数和初始膜厚度下，这种影响更为明显。最后，以流变特性的生理值为基线，研究了流变特性对壁应力的独立影响。
