Implementation of a specific boundary condition for a simplified symmetric single-path CFD lung model with OpenFOAM
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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.
KeywordsBoundary condition CFD Human airways OpenFOAM® Single airway Truncated branches
Authors acknowledge that this work was partially funded by the Spanish Ministry of Economy, Industry and Competitiveness—Instituto de Salud Carlos III under Project “Estudio de la influencia de la geometría de las vías respiratorias en las patologías pulmonares obstructivas (PI17/01639)” and was supported by Universidad de Oviedo under Project “Desarrollo de nuevo material docente sobre flujos biológicos: simulación de vías áreas humanas. PINN-17-A-061.” and by Junta de Extremadura through Grant IB16119 (partially financed by FEDER).
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Conflict of interest
The authors declare that they have no conflict of interest.
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