Anatomical airways parameters, such as length, diameter and angles, have a strong effect on the flow dynamics. Aiming to explore the effect of variations of the bifurcation angle (BA) and carina rounding radius (CRR) of lower human airways on respiratory processes, numerical simulations of airflow during inhalation and exhalation were performed using synthetic bifurcation models. Geometries for the airways models were parameterized based on a set of different BA’s and several CRR’s. A range of Reynolds numbers (Re), relevant to the human breathing process, were selected to analyze airflow behavior. The numerical results showed a significant influence of BA and the CRR on the development of the airflow within the airways, and, therefore, affecting the following relevant features of the flow: the deformation of velocity profiles, alterations of pressure drop, flow patterns, and, finally, enhancement or attenuation of wall shear stresses (WSS) appearing during the regular respiratory process. The numerical results showed that increases in the bifurcation angle value were accompanied by pressure increases of about 20%, especially in the regions close to the bifurcation. Similarly, increases in the BA value led to a reduction in peak shear stresses of up to 70%. For the ranges of angles and radii explored, an increase in pressure of about 20% and a reduction in wall shear stress of more than 400% were obtained by increasing the carina rounding radius. Analysis of the coherent structures and secondary flow patterns also revealed a direct relationship between the location of the vortical structures, the local maxima of the velocity profiles and the local vorticity minima. This relationship was observed for all branches analyzed, for both the inhalation and exhalation processes of the respiratory cycle.
Anatomical airways parameters as length, diameter and angles have a strong effect on the flow dynamics. Aiming to explore the effect of variations of the bifurcation angle (BA) and carina rounding radius (CRR) of lower human airways on the respiratory processes, numerical simulations of airflow during inhalation and exhalation were performed using a synthetic bifurcation models. Geometries for the airways models were parameterized based on a set of different BA's and several CRR's. A range of Reynolds numbers (\Reyn) relevant to the human breathing process were selected to analyzed the airflow behaviour. The numerical results show a significant influence of BA and the CRR on the development of the airflow within the airways, and therefore affecting some relevant features of the flow, namely the deformation of velocity profiles, alterations of pressure drop, the flow patterns, and finally enhance or attenuation of wall shear stresses (WSS) appearing during the regular respiratory process. Numerical results show that increases in the bifurcation angle value are accompanied by pressure increases of about 20\%, especially in the regions close to the bifurcation. Similarly, increases in the BA value lead to a reduction in peak shear stresses of up to 70\%. For the ranges of angles and radii explored, an increase in pressure of about 20\% and a reduction in wall shear stress of more than 400\% were obtained by increasing the carina rounding radius. Analysis of the coherent structures and secondary flow patterns also revealed a direct relationship between the location of the vortical structures, the local maxima of the velocity profiles and the local vorticity minima. This relationship was observed for all branches analysed, for both the inhalation and exhalation processes of the respiratory cycle.
Anatomical airways parameters as length, diameter and angles have a strong effect on the flow dynamics. Aiming to explore the effect of variations of the bifurcation angle (BA) and carina rounding radius (CRR) of lower human airways on the respiratory processes, numerical simulations of airflow during inhalation and exhalation were performed using a synthetic bifurcation models. Geometries for the airways models were parameterized based on a set of different BA’s and several CRR’s. A range of Reynolds numbers (Re) relevant to the human breathing process were selected to analyzed the airflow behaviour. The numerical results show a significant influence of BA and the CRR on the development of the airflow within the airways, and therefore affecting some relevant features of the flow, namely the deformation of velocity profiles, alterations of pressure drop, the secondary flow patterns, and finally enhance or attenuation of wall shear stresses (WSS) appearing during the regular respiratory process. A particular relationship between velocity profiles, vorticity and the secondary flow patterns is also discussed.
Este artículo puede compartirse bajo la licencia CC BY-ND 4.0 y se referencia usando el siguiente formato: S. Espinosa, C. Duque, "Efecto del ángulo de redondeo de carina en el desarrollo del flujo a través de un modelo sintético de vías respiratorias," Rev. Efecto del radio de redondeo de la carina en el desarrollo del flujo a través de un modelo sintético de vías respiratorias Effect of rounding radius of the carina on the development of the flow within a synthetic model of lower human airways ResumenEl efecto del radio de redondeo de la carina durante el proceso de inhalación es explorado numéricamente mediante simulaciones computacionales basadas en un modelo sintético de vías respiratorias. Las geometrías son parametrizadas en términos de la curvatura adimensional de carina. En el presente estudio se exploraron dos números de Reynolds en régimen laminar. Los resultados obtenidos muestran que la variación de este parámetro fisiológico afecta la magnitud y distribución de los esfuerzos cortantes de pared, así como el comportamiento de las estructuras vorticales observadas en el flujo secundario. Este parámetro afecta también, aunque en menor medida, las caídas de presión a través de las ramificaciones. Igualmente se discuten algunos efectos producidos por la variación de dicha curvatura sobre aspectos fisiológicos del proceso de respiración. Finalmente, se hace una breve reflexión acerca de las ventajas del uso de técnicas de simulación computacional CFD para el estudio de fenómenos asociados a biofluidos.Palabras clave: biofluidos; carina; dinámica de fluidos computacional (CFD). AbstractThe effect of the rounding radius of the Carina, during inhalation stage for the respiration process, was explored numerically through computational simulations based on a synthetic model of human airways. The geometries were parameterized in terms of the dimensionless curvature of carina. In the present study, two Reynolds numbers were explored in laminar flow regime. The results show that the variation of this physiological parameter affects the magnitude and distribution of the wall shear stresses, as well as the behavior of vortical structures observed in the secondary flow. This parameter also affects, although to a lesser extent, the pressure drops across the branches. The effects produced by the variation of this curvature on physiological aspects of the breathing process are analyzed. Finally, a brief discussion about the advantages of the use of CFD simulation techniques for the study of phenomena associated to biofluids is presented.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.