Departamento de Energía, Universidad de Oviedo, Oviedo, Spain.
Departamento de IMEM, Universidad de Extremadura, Badajoz, Spain.
Biomech Model Mechanobiol. 2019 Dec;18(6):1759-1771. doi: 10.1007/s10237-019-01174-w. Epub 2019 Jun 1.
CFD modeling research about the lung airflow with a complete resolution and an adequate accuracy at all scales requires a great amount of computational resources due to the vast number of necessary grid elements. As a result, a common practice is to conduct simplifications that allows to manage it with ordinary computational power. In this study, the implementation of a special boundary condition in order to develop a simplified single conductive lung airway model, which exactly represents the effect of the removed airways, is presented. The boundary condition is programmed in the open-source software OpenFOAM®, and the developed source code is presented in the proper syntax. After this description, modeling accuracy is evaluated under different flow rate conditions typical of human breathing processes, including both inspiration and expiration movements. Afterward, a validation process is conducted using results of a Weibel's model (0-4 generations) simulation for a medium flow rate of 50 L/min. Finally, a comparison against the proposed boundary condition implemented in the commercial code ANSYS Fluent is made, which highlights the benefits of using the free code toolbox. The specific contribution of this paper will be to show that OpenFOAM® developed model can perform even better than other commercial codes due to a precise implementation and coupling of the default solver with the in-house functions by virtue of the open-source nature of the code.
CFD 建模研究表明，由于需要大量的网格元素，要完整解析并在所有尺度上达到足够的精度，都需要大量的计算资源。因此，通常的做法是进行简化，以便用普通的计算能力来处理。在本研究中，提出了一种特殊边界条件的实现方法，以开发一种简化的单传导肺气道模型，该模型可以准确地表示去除气道的影响。边界条件是在开源软件 OpenFOAM®中编程的，开发的源代码用适当的语法表示。在描述之后，根据人类呼吸过程的典型流量条件（包括吸气和呼气运动）评估建模精度。之后，使用中流量 50 L/min 的 Weibel 模型（0-4 代）模拟进行验证过程。最后，与商业代码 ANSYS Fluent 中实现的拟边界条件进行比较，突出了使用免费代码工具包的优势。本文的具体贡献在于，由于代码的开源性质，OpenFOAM®开发的模型可以通过默认求解器与内部函数的精确实现和耦合，甚至比其他商业代码表现更好。
