Computer Methods and Programs in Biomedicine, Feb 1, 2022
BACKGROUND AND OBJECTIVE Neonates are preferential nasal breathers up to 3 months of age. The nas... more BACKGROUND AND OBJECTIVE Neonates are preferential nasal breathers up to 3 months of age. The nasal anatomy in neonates and infants is at developing stages whereas the adult nasal cavities are fully grown which implies that the study of airflow dynamics in the neonates and infants are significant. In the present study, the nasal airways of the neonate, infant and adult are anatomically compared and their airflow patterns are investigated. METHODS Computational Fluid Dynamics (CFD) approach is used to simulate the airflow in a neonate, an infant and an adult in sedentary breathing conditions. The healthy CT scans are segmented using MIMICS 21.0 (Materialise, Ann arbor, MI). The patient-specific 3D airway models are analyzed for low Reynolds number flow using ANSYS FLUENT 2020 R2. The applicability of the Grid Convergence Index (GCI) for polyhedral mesh adopted in this work is also verified. RESULTS This study shows that the inferior meatus of neonates accounted for only 15% of the total airflow. This was in contrast to the infants and adults who experienced 49 and 31% of airflow at the inferior meatus region. Superior meatus experienced 25% of total flow which is more than normal for the neonate. The highest velocity of 1.8, 2.6 and 3.7 m/s was observed at the nasal valve region for neonates, infants and adults, respectively. The anterior portion of the nasal cavity experienced maximum wall shear stress with average values of 0.48, 0.25 and 0.58 Pa for the neonates, infants and adults. CONCLUSIONS The neonates have an underdeveloped nasal cavity which significantly affects their airway distribution. The absence of inferior meatus in the neonates has limited the flow through the inferior regions and resulted in uneven flow distribution.
Fatigue failure is one of the causes of the failure of hip implants. The main objective of this w... more Fatigue failure is one of the causes of the failure of hip implants. The main objective of this work is to carry out fatigue failure analysis on different hip profiles and compare the outcomes for various combinations of materials. Three profiles each for circular, oval, elliptical, and trapezoidal stems are utilized for this study with four different material combinations consisting of materials like Ti-6Al-4V, CoCr Alloy and UHMWPE. CATIA V-6 is used for the modelling of these implants and the fatigue analysis using Goodman's mean stress theory is simulated using ANSYS 2022 R1. ISO 7206-4 and ASTM F2996-13 standards are used to define the boundary conditions. A total of 48 combinations were studied across four different shapes, three different profiles and four different material combinations to deduce the best possible combination for a hip implant for static and fatigue loading. Comparison of the implants is based on the factors like equivalent von Mises stress, displacement...
Background and objective: Causes for nasal airway obstruction (NAO) are many but septum deviation... more Background and objective: Causes for nasal airway obstruction (NAO) are many but septum deviation is the most prevalent etiology. A deviated septum affects the airflow dynamics in the human nasal cavity, which in turn affects the physiological functions of the nasal cavity like heating, humidification, and filtration capabilities. The present study investigates and compares the airflow patterns in a healthy nasal cavity to a septal deviated nasal cavity.Methods: Two nasal airway models are considered and compared in this study. One with a septal deviation and the second with a healthy patent nasal cavity. Airflow analysis is carried out by developing the CT scans into 3D models using Materialise MIMICS (Materialise, Ann Arbor, MI), and then using the FLUENT solver of ANSYS 2020R2. The simulations are carried out for airflows ranging in laminar and turbulent flows using the SST k-ω turbulence model. Polyhedral meshes are used and the mesh check using Grid Convergence Index studies is...
Computer Methods and Programs in Biomedicine, 2021
BACKGROUND AND OBJECTIVE Neonates are preferential nasal breathers up to 3 months of age. The nas... more BACKGROUND AND OBJECTIVE Neonates are preferential nasal breathers up to 3 months of age. The nasal anatomy in neonates and infants is at developing stages whereas the adult nasal cavities are fully grown which implies that the study of airflow dynamics in the neonates and infants are significant. In the present study, the nasal airways of the neonate, infant and adult are anatomically compared and their airflow patterns are investigated. METHODS Computational Fluid Dynamics (CFD) approach is used to simulate the airflow in a neonate, an infant and an adult in sedentary breathing conditions. The healthy CT scans are segmented using MIMICS 21.0 (Materialise, Ann arbor, MI). The patient-specific 3D airway models are analyzed for low Reynolds number flow using ANSYS FLUENT 2020 R2. The applicability of the Grid Convergence Index (GCI) for polyhedral mesh adopted in this work is also verified. RESULTS This study shows that the inferior meatus of neonates accounted for only 15% of the total airflow. This was in contrast to the infants and adults who experienced 49 and 31% of airflow at the inferior meatus region. Superior meatus experienced 25% of total flow which is more than normal for the neonate. The highest velocity of 1.8, 2.6 and 3.7 m/s was observed at the nasal valve region for neonates, infants and adults, respectively. The anterior portion of the nasal cavity experienced maximum wall shear stress with average values of 0.48, 0.25 and 0.58 Pa for the neonates, infants and adults. CONCLUSIONS The neonates have an underdeveloped nasal cavity which significantly affects their airway distribution. The absence of inferior meatus in the neonates has limited the flow through the inferior regions and resulted in uneven flow distribution.
Computer Methods and Programs in Biomedicine, Feb 1, 2022
BACKGROUND AND OBJECTIVE Neonates are preferential nasal breathers up to 3 months of age. The nas... more BACKGROUND AND OBJECTIVE Neonates are preferential nasal breathers up to 3 months of age. The nasal anatomy in neonates and infants is at developing stages whereas the adult nasal cavities are fully grown which implies that the study of airflow dynamics in the neonates and infants are significant. In the present study, the nasal airways of the neonate, infant and adult are anatomically compared and their airflow patterns are investigated. METHODS Computational Fluid Dynamics (CFD) approach is used to simulate the airflow in a neonate, an infant and an adult in sedentary breathing conditions. The healthy CT scans are segmented using MIMICS 21.0 (Materialise, Ann arbor, MI). The patient-specific 3D airway models are analyzed for low Reynolds number flow using ANSYS FLUENT 2020 R2. The applicability of the Grid Convergence Index (GCI) for polyhedral mesh adopted in this work is also verified. RESULTS This study shows that the inferior meatus of neonates accounted for only 15% of the total airflow. This was in contrast to the infants and adults who experienced 49 and 31% of airflow at the inferior meatus region. Superior meatus experienced 25% of total flow which is more than normal for the neonate. The highest velocity of 1.8, 2.6 and 3.7 m/s was observed at the nasal valve region for neonates, infants and adults, respectively. The anterior portion of the nasal cavity experienced maximum wall shear stress with average values of 0.48, 0.25 and 0.58 Pa for the neonates, infants and adults. CONCLUSIONS The neonates have an underdeveloped nasal cavity which significantly affects their airway distribution. The absence of inferior meatus in the neonates has limited the flow through the inferior regions and resulted in uneven flow distribution.
Fatigue failure is one of the causes of the failure of hip implants. The main objective of this w... more Fatigue failure is one of the causes of the failure of hip implants. The main objective of this work is to carry out fatigue failure analysis on different hip profiles and compare the outcomes for various combinations of materials. Three profiles each for circular, oval, elliptical, and trapezoidal stems are utilized for this study with four different material combinations consisting of materials like Ti-6Al-4V, CoCr Alloy and UHMWPE. CATIA V-6 is used for the modelling of these implants and the fatigue analysis using Goodman's mean stress theory is simulated using ANSYS 2022 R1. ISO 7206-4 and ASTM F2996-13 standards are used to define the boundary conditions. A total of 48 combinations were studied across four different shapes, three different profiles and four different material combinations to deduce the best possible combination for a hip implant for static and fatigue loading. Comparison of the implants is based on the factors like equivalent von Mises stress, displacement...
Background and objective: Causes for nasal airway obstruction (NAO) are many but septum deviation... more Background and objective: Causes for nasal airway obstruction (NAO) are many but septum deviation is the most prevalent etiology. A deviated septum affects the airflow dynamics in the human nasal cavity, which in turn affects the physiological functions of the nasal cavity like heating, humidification, and filtration capabilities. The present study investigates and compares the airflow patterns in a healthy nasal cavity to a septal deviated nasal cavity.Methods: Two nasal airway models are considered and compared in this study. One with a septal deviation and the second with a healthy patent nasal cavity. Airflow analysis is carried out by developing the CT scans into 3D models using Materialise MIMICS (Materialise, Ann Arbor, MI), and then using the FLUENT solver of ANSYS 2020R2. The simulations are carried out for airflows ranging in laminar and turbulent flows using the SST k-ω turbulence model. Polyhedral meshes are used and the mesh check using Grid Convergence Index studies is...
Computer Methods and Programs in Biomedicine, 2021
BACKGROUND AND OBJECTIVE Neonates are preferential nasal breathers up to 3 months of age. The nas... more BACKGROUND AND OBJECTIVE Neonates are preferential nasal breathers up to 3 months of age. The nasal anatomy in neonates and infants is at developing stages whereas the adult nasal cavities are fully grown which implies that the study of airflow dynamics in the neonates and infants are significant. In the present study, the nasal airways of the neonate, infant and adult are anatomically compared and their airflow patterns are investigated. METHODS Computational Fluid Dynamics (CFD) approach is used to simulate the airflow in a neonate, an infant and an adult in sedentary breathing conditions. The healthy CT scans are segmented using MIMICS 21.0 (Materialise, Ann arbor, MI). The patient-specific 3D airway models are analyzed for low Reynolds number flow using ANSYS FLUENT 2020 R2. The applicability of the Grid Convergence Index (GCI) for polyhedral mesh adopted in this work is also verified. RESULTS This study shows that the inferior meatus of neonates accounted for only 15% of the total airflow. This was in contrast to the infants and adults who experienced 49 and 31% of airflow at the inferior meatus region. Superior meatus experienced 25% of total flow which is more than normal for the neonate. The highest velocity of 1.8, 2.6 and 3.7 m/s was observed at the nasal valve region for neonates, infants and adults, respectively. The anterior portion of the nasal cavity experienced maximum wall shear stress with average values of 0.48, 0.25 and 0.58 Pa for the neonates, infants and adults. CONCLUSIONS The neonates have an underdeveloped nasal cavity which significantly affects their airway distribution. The absence of inferior meatus in the neonates has limited the flow through the inferior regions and resulted in uneven flow distribution.
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