The Experts below are selected from a list of 19329 Experts worldwide ranked by ideXlab platform
Ephraim Gutmark - One of the best experts on this subject based on the ideXlab platform.
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planning human upper Airway surgery using computational fluid dynamics
Journal of Biomechanics, 2013Co-Authors: Goutham Mylavarapu, Mihai Mihaescu, Laszlo Fuchs, Georgios Papatziamos, Ephraim GutmarkAbstract:The study advances the idea of using computational fluid dynamics in the process of planning surgical treatment modalities for patients with obstructive Airway disorders. It is hypothesized that the a priori knowledge of the functional outcome of surgical intervention on the Flow and Airway resistance can guide the surgeon in choosing an effective surgical strategy. Computed tomography images spanning the respiratory tract of an adult patient with a combined glottic and subglottic stenosis are used to reconstruct three-dimensional geometrical models of the Airway. Computational fluid dynamics is used to obtain Airway Flow patterns during inspiration and expiration in these models. Numerical predictions about Flow velocity, pressure distribution on the Airway lumen, wall shear stress, and Airway resistance are obtained so that the relevance of each individual stenotic level is quantified. Four different virtual surgeries in different combinations are assessed in order to remedy the constricted Airway. The virtual surgery based Airway models are evaluated by comparisons with the pre-treatment Flow modeling results. The predicted numerical data revealed that the removal of the constriction at the level of the vocal folds will have the most significant effect on the Airway resistance. The Flow simulations offer a quantitative method of evaluating the Airway resistance in patients with combined glottic and subglottic stenoses. Predictions of Airway resistances and other numerical calculations from different virtual surgeries give additional inputs for the surgeon, in deciding the most appropriate surgery on a case-by-case basis.
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validation of computational fluid dynamics methodology used for human upper Airway Flow simulations
Journal of Biomechanics, 2009Co-Authors: Goutham Mylavarapu, Shanmugam Murugappan, Mihai Mihaescu, Maninder Kalra, Sid Khosla, Ephraim GutmarkAbstract:An anatomically accurate human upper Airway model was constructed from multiple magnetic resonance imaging axial scans. This model was used to conduct detailed Computational Fluid Dynamics (CFD) simulations during expiration, to investigate the fluid Flow in the Airway regions where obstruction could occur. An identical physical model of the same Airway was built using stereo lithography. Pressure and velocity measurements were conducted in the physical model. Both simulations and experiments were performed at a peak expiratory Flow rate of 200 L/min. Several different numerical approaches within the FLUENT commercial software framework were used in the simulations; unsteady Large Eddy Simulation (LES), steady Reynolds-Averaged Navier-Stokes (RANS) with two-equation turbulence models (i.e. k-epsilon, standard k-omega, and k-omega Shear Stress Transport (SST)) and with one-equation Spalart-Allmaras model. The CFD predictions of the average wall static pressures at different locations along the Airway wall were favorably compared with the experimental data. Among all the approaches, standard k-omega turbulence model resulted in the best agreement with the static pressure measurements, with an average error of approximately 20% over all ports. The highest positive pressures were observed in the retroglossal regions below the epiglottis, while the lowest negative pressures were recorded in the retropalatal region. The latter is a result of the airFlow acceleration in the narrow retropalatal region. The largest pressure drop was observed at the tip of the soft palate. This location has the smallest cross section of the Airway. The good agreement between the computations and the experimental results suggest that CFD simulations can be used to accurately compute aerodynamic Flow characteristics of the upper Airway.
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validation of computational fluid dynamics methodology used for human upper Airway Flow simulations
Journal of Biomechanics, 2009Co-Authors: Goutham Mylavarapu, Shanmugam Murugappan, Mihai Mihaescu, Maninder Kalra, Sid Khosla, Ephraim GutmarkAbstract:Abstract An anatomically accurate human upper Airway model was constructed from multiple magnetic resonance imaging axial scans. This model was used to conduct detailed Computational Fluid Dynamics (CFD) simulations during expiration, to investigate the fluid Flow in the Airway regions where obstruction could occur. An identical physical model of the same Airway was built using stereo lithography. Pressure and velocity measurements were conducted in the physical model. Both simulations and experiments were performed at a peak expiratory Flow rate of 200 L/min. Several different numerical approaches within the FLUENT commercial software framework were used in the simulations; unsteady Large Eddy Simulation (LES), steady Reynolds-Averaged Navier-Stokes (RANS) with two-equation turbulence models (i.e. k − e , standard k − ω , and k − ω Shear Stress Transport (SST)) and with one-equation Spalart–Allmaras model. The CFD predictions of the average wall static pressures at different locations along the Airway wall were favorably compared with the experimental data. Among all the approaches, standard k − ω turbulence model resulted in the best agreement with the static pressure measurements, with an average error of ∼20% over all ports. The highest positive pressures were observed in the retroglossal regions below the epiglottis, while the lowest negative pressures were recorded in the retropalatal region. The latter is a result of the airFlow acceleration in the narrow retropalatal region. The largest pressure drop was observed at the tip of the soft palate. This location has the smallest cross section of the Airway. The good agreement between the computations and the experimental results suggest that CFD simulations can be used to accurately compute aerodynamic Flow characteristics of the upper Airway.
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computational modeling of upper Airway before and after adenotonsillectomy for obstructive sleep apnea
Laryngoscope, 2008Co-Authors: Mihai Mihaescu, Shanmugam Murugappan, Ephraim Gutmark, Lane F Donnelly, Maninder KalraAbstract:Adenotonsillectomy, the first-line surgical treatment for obstructive sleep apnea (OSA) in children, is successful in only 50% of obese children. Computational fluid dynamics tools, which have been applied to differentiate OSA patients from those without OSA based on the Airway Flow characteristics, can be potentially used to identify patients likely to benefit from surgical intervention. We present computational modeling of the upper Airway before and after adenotonsillectomy in an obese female adolescent with OSA. The subject underwent upper Airway imaging on a 1.5 Tesla magnetic resonance imaging (MRI) scanner, and three-dimensional Airway models were constructed using Airway boundary coordinates from cross-sectional MRI scans. Our results using computational simulations indicate that, in an obese child, the resolution of OSA after adenotonsillectomy is associated with changes in Flow characteristics that result in decreased pressure differentials across the Airway walls and thus lower compressive forces that predispose to Airway collapse. Application of such findings to an obese child seeking surgical treatment for OSA can potentially lead to selection of the surgical procedure most likely to result in OSA resolution. Effective intervention for OSA in this high-risk group will result in reduction in morbidity and the public health concerns associated with OSA.
Shaokoon Cheng - One of the best experts on this subject based on the ideXlab platform.
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potential effects of lingual fats on Airway Flow dynamics and particle deposition
Aerosol Science and Technology, 2020Co-Authors: Agisilaos Kourmatzis, Yongling Zhao, Runyu Yang, Hakkim Chan, Fatemeh Salehi, Shaokoon ChengAbstract:AbstractFat content on upper Airway soft tissue can alter the geometry of the human pharynx, most notably by narrowing the upper Airway at the level of the epiglottis. Despite the important role of...
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the effects of upper Airway tissue motion on airFlow dynamics
Journal of Biomechanics, 2020Co-Authors: Yongling Zhao, Agisilaos Kourmatzis, Runyu Yang, Hakkim Chan, Joel Raco, Sammy Diasinos, Shaokoon ChengAbstract:The human upper Airway is not only geometrically complex, but it can also deform dynamically as a result of active muscle contraction and motility during respiration. How the active transformation of the Airway geometry affects airFlow dynamics during respiration is not well understood despite the importance of this knowledge towards improving current understanding of particle transport and deposition. In this study, particle imaging velocimetry (PIV) measurements of the fluid dynamics are presented in a physiologically realistic human upper Airway replica for (i) the undeformed case and (ii) the case where realistic soft tissue motion during breathing is emulated. Results from this study show that extrathoracic wall motion alters the Flow field significantly such that the fluid dynamics is distinctly different from the undeformed Airway. Distinctive Flow field patterns in the physiologically realistic Airway include (i) fluid recirculation at the back of the tongue and cranial to the tip of the epiglottis during mid-inspiration, (ii) horizontal and posteriorly directed Flow at the back of tongue at the peak of inspiration and (iii) a more homogeneous Flow across the Airway downstream from the epiglottis. These findings suggest that the active deformation of the human upper Airway may potentially influence particle transport and deposition at the back of the tongue and therefore, highlights the importance of considering extrathoracic wall motion in future Airway Flow studies. D.
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Airway geometry Airway Flow and particle measurement methods implications on pulmonary drug delivery
Expert Opinion on Drug Delivery, 2018Co-Authors: Agisilaos Kourmatzis, Shaokoon Cheng, Hakkim ChanAbstract:ABSTRACTIntroduction: The effectiveness of drug delivery to the lungs is inextricably linked to the fundamental interactions that occur between particles and Flow in the extrathoracic Airway. Resea...
Mihai Mihaescu - One of the best experts on this subject based on the ideXlab platform.
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planning human upper Airway surgery using computational fluid dynamics
Journal of Biomechanics, 2013Co-Authors: Goutham Mylavarapu, Mihai Mihaescu, Laszlo Fuchs, Georgios Papatziamos, Ephraim GutmarkAbstract:The study advances the idea of using computational fluid dynamics in the process of planning surgical treatment modalities for patients with obstructive Airway disorders. It is hypothesized that the a priori knowledge of the functional outcome of surgical intervention on the Flow and Airway resistance can guide the surgeon in choosing an effective surgical strategy. Computed tomography images spanning the respiratory tract of an adult patient with a combined glottic and subglottic stenosis are used to reconstruct three-dimensional geometrical models of the Airway. Computational fluid dynamics is used to obtain Airway Flow patterns during inspiration and expiration in these models. Numerical predictions about Flow velocity, pressure distribution on the Airway lumen, wall shear stress, and Airway resistance are obtained so that the relevance of each individual stenotic level is quantified. Four different virtual surgeries in different combinations are assessed in order to remedy the constricted Airway. The virtual surgery based Airway models are evaluated by comparisons with the pre-treatment Flow modeling results. The predicted numerical data revealed that the removal of the constriction at the level of the vocal folds will have the most significant effect on the Airway resistance. The Flow simulations offer a quantitative method of evaluating the Airway resistance in patients with combined glottic and subglottic stenoses. Predictions of Airway resistances and other numerical calculations from different virtual surgeries give additional inputs for the surgeon, in deciding the most appropriate surgery on a case-by-case basis.
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validation of computational fluid dynamics methodology used for human upper Airway Flow simulations
Journal of Biomechanics, 2009Co-Authors: Goutham Mylavarapu, Shanmugam Murugappan, Mihai Mihaescu, Maninder Kalra, Sid Khosla, Ephraim GutmarkAbstract:An anatomically accurate human upper Airway model was constructed from multiple magnetic resonance imaging axial scans. This model was used to conduct detailed Computational Fluid Dynamics (CFD) simulations during expiration, to investigate the fluid Flow in the Airway regions where obstruction could occur. An identical physical model of the same Airway was built using stereo lithography. Pressure and velocity measurements were conducted in the physical model. Both simulations and experiments were performed at a peak expiratory Flow rate of 200 L/min. Several different numerical approaches within the FLUENT commercial software framework were used in the simulations; unsteady Large Eddy Simulation (LES), steady Reynolds-Averaged Navier-Stokes (RANS) with two-equation turbulence models (i.e. k-epsilon, standard k-omega, and k-omega Shear Stress Transport (SST)) and with one-equation Spalart-Allmaras model. The CFD predictions of the average wall static pressures at different locations along the Airway wall were favorably compared with the experimental data. Among all the approaches, standard k-omega turbulence model resulted in the best agreement with the static pressure measurements, with an average error of approximately 20% over all ports. The highest positive pressures were observed in the retroglossal regions below the epiglottis, while the lowest negative pressures were recorded in the retropalatal region. The latter is a result of the airFlow acceleration in the narrow retropalatal region. The largest pressure drop was observed at the tip of the soft palate. This location has the smallest cross section of the Airway. The good agreement between the computations and the experimental results suggest that CFD simulations can be used to accurately compute aerodynamic Flow characteristics of the upper Airway.
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validation of computational fluid dynamics methodology used for human upper Airway Flow simulations
Journal of Biomechanics, 2009Co-Authors: Goutham Mylavarapu, Shanmugam Murugappan, Mihai Mihaescu, Maninder Kalra, Sid Khosla, Ephraim GutmarkAbstract:Abstract An anatomically accurate human upper Airway model was constructed from multiple magnetic resonance imaging axial scans. This model was used to conduct detailed Computational Fluid Dynamics (CFD) simulations during expiration, to investigate the fluid Flow in the Airway regions where obstruction could occur. An identical physical model of the same Airway was built using stereo lithography. Pressure and velocity measurements were conducted in the physical model. Both simulations and experiments were performed at a peak expiratory Flow rate of 200 L/min. Several different numerical approaches within the FLUENT commercial software framework were used in the simulations; unsteady Large Eddy Simulation (LES), steady Reynolds-Averaged Navier-Stokes (RANS) with two-equation turbulence models (i.e. k − e , standard k − ω , and k − ω Shear Stress Transport (SST)) and with one-equation Spalart–Allmaras model. The CFD predictions of the average wall static pressures at different locations along the Airway wall were favorably compared with the experimental data. Among all the approaches, standard k − ω turbulence model resulted in the best agreement with the static pressure measurements, with an average error of ∼20% over all ports. The highest positive pressures were observed in the retroglossal regions below the epiglottis, while the lowest negative pressures were recorded in the retropalatal region. The latter is a result of the airFlow acceleration in the narrow retropalatal region. The largest pressure drop was observed at the tip of the soft palate. This location has the smallest cross section of the Airway. The good agreement between the computations and the experimental results suggest that CFD simulations can be used to accurately compute aerodynamic Flow characteristics of the upper Airway.
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computational modeling of upper Airway before and after adenotonsillectomy for obstructive sleep apnea
Laryngoscope, 2008Co-Authors: Mihai Mihaescu, Shanmugam Murugappan, Ephraim Gutmark, Lane F Donnelly, Maninder KalraAbstract:Adenotonsillectomy, the first-line surgical treatment for obstructive sleep apnea (OSA) in children, is successful in only 50% of obese children. Computational fluid dynamics tools, which have been applied to differentiate OSA patients from those without OSA based on the Airway Flow characteristics, can be potentially used to identify patients likely to benefit from surgical intervention. We present computational modeling of the upper Airway before and after adenotonsillectomy in an obese female adolescent with OSA. The subject underwent upper Airway imaging on a 1.5 Tesla magnetic resonance imaging (MRI) scanner, and three-dimensional Airway models were constructed using Airway boundary coordinates from cross-sectional MRI scans. Our results using computational simulations indicate that, in an obese child, the resolution of OSA after adenotonsillectomy is associated with changes in Flow characteristics that result in decreased pressure differentials across the Airway walls and thus lower compressive forces that predispose to Airway collapse. Application of such findings to an obese child seeking surgical treatment for OSA can potentially lead to selection of the surgical procedure most likely to result in OSA resolution. Effective intervention for OSA in this high-risk group will result in reduction in morbidity and the public health concerns associated with OSA.
Maninder Kalra - One of the best experts on this subject based on the ideXlab platform.
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validation of computational fluid dynamics methodology used for human upper Airway Flow simulations
Journal of Biomechanics, 2009Co-Authors: Goutham Mylavarapu, Shanmugam Murugappan, Mihai Mihaescu, Maninder Kalra, Sid Khosla, Ephraim GutmarkAbstract:An anatomically accurate human upper Airway model was constructed from multiple magnetic resonance imaging axial scans. This model was used to conduct detailed Computational Fluid Dynamics (CFD) simulations during expiration, to investigate the fluid Flow in the Airway regions where obstruction could occur. An identical physical model of the same Airway was built using stereo lithography. Pressure and velocity measurements were conducted in the physical model. Both simulations and experiments were performed at a peak expiratory Flow rate of 200 L/min. Several different numerical approaches within the FLUENT commercial software framework were used in the simulations; unsteady Large Eddy Simulation (LES), steady Reynolds-Averaged Navier-Stokes (RANS) with two-equation turbulence models (i.e. k-epsilon, standard k-omega, and k-omega Shear Stress Transport (SST)) and with one-equation Spalart-Allmaras model. The CFD predictions of the average wall static pressures at different locations along the Airway wall were favorably compared with the experimental data. Among all the approaches, standard k-omega turbulence model resulted in the best agreement with the static pressure measurements, with an average error of approximately 20% over all ports. The highest positive pressures were observed in the retroglossal regions below the epiglottis, while the lowest negative pressures were recorded in the retropalatal region. The latter is a result of the airFlow acceleration in the narrow retropalatal region. The largest pressure drop was observed at the tip of the soft palate. This location has the smallest cross section of the Airway. The good agreement between the computations and the experimental results suggest that CFD simulations can be used to accurately compute aerodynamic Flow characteristics of the upper Airway.
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validation of computational fluid dynamics methodology used for human upper Airway Flow simulations
Journal of Biomechanics, 2009Co-Authors: Goutham Mylavarapu, Shanmugam Murugappan, Mihai Mihaescu, Maninder Kalra, Sid Khosla, Ephraim GutmarkAbstract:Abstract An anatomically accurate human upper Airway model was constructed from multiple magnetic resonance imaging axial scans. This model was used to conduct detailed Computational Fluid Dynamics (CFD) simulations during expiration, to investigate the fluid Flow in the Airway regions where obstruction could occur. An identical physical model of the same Airway was built using stereo lithography. Pressure and velocity measurements were conducted in the physical model. Both simulations and experiments were performed at a peak expiratory Flow rate of 200 L/min. Several different numerical approaches within the FLUENT commercial software framework were used in the simulations; unsteady Large Eddy Simulation (LES), steady Reynolds-Averaged Navier-Stokes (RANS) with two-equation turbulence models (i.e. k − e , standard k − ω , and k − ω Shear Stress Transport (SST)) and with one-equation Spalart–Allmaras model. The CFD predictions of the average wall static pressures at different locations along the Airway wall were favorably compared with the experimental data. Among all the approaches, standard k − ω turbulence model resulted in the best agreement with the static pressure measurements, with an average error of ∼20% over all ports. The highest positive pressures were observed in the retroglossal regions below the epiglottis, while the lowest negative pressures were recorded in the retropalatal region. The latter is a result of the airFlow acceleration in the narrow retropalatal region. The largest pressure drop was observed at the tip of the soft palate. This location has the smallest cross section of the Airway. The good agreement between the computations and the experimental results suggest that CFD simulations can be used to accurately compute aerodynamic Flow characteristics of the upper Airway.
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computational modeling of upper Airway before and after adenotonsillectomy for obstructive sleep apnea
Laryngoscope, 2008Co-Authors: Mihai Mihaescu, Shanmugam Murugappan, Ephraim Gutmark, Lane F Donnelly, Maninder KalraAbstract:Adenotonsillectomy, the first-line surgical treatment for obstructive sleep apnea (OSA) in children, is successful in only 50% of obese children. Computational fluid dynamics tools, which have been applied to differentiate OSA patients from those without OSA based on the Airway Flow characteristics, can be potentially used to identify patients likely to benefit from surgical intervention. We present computational modeling of the upper Airway before and after adenotonsillectomy in an obese female adolescent with OSA. The subject underwent upper Airway imaging on a 1.5 Tesla magnetic resonance imaging (MRI) scanner, and three-dimensional Airway models were constructed using Airway boundary coordinates from cross-sectional MRI scans. Our results using computational simulations indicate that, in an obese child, the resolution of OSA after adenotonsillectomy is associated with changes in Flow characteristics that result in decreased pressure differentials across the Airway walls and thus lower compressive forces that predispose to Airway collapse. Application of such findings to an obese child seeking surgical treatment for OSA can potentially lead to selection of the surgical procedure most likely to result in OSA resolution. Effective intervention for OSA in this high-risk group will result in reduction in morbidity and the public health concerns associated with OSA.
Goutham Mylavarapu - One of the best experts on this subject based on the ideXlab platform.
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planning human upper Airway surgery using computational fluid dynamics
Journal of Biomechanics, 2013Co-Authors: Goutham Mylavarapu, Mihai Mihaescu, Laszlo Fuchs, Georgios Papatziamos, Ephraim GutmarkAbstract:The study advances the idea of using computational fluid dynamics in the process of planning surgical treatment modalities for patients with obstructive Airway disorders. It is hypothesized that the a priori knowledge of the functional outcome of surgical intervention on the Flow and Airway resistance can guide the surgeon in choosing an effective surgical strategy. Computed tomography images spanning the respiratory tract of an adult patient with a combined glottic and subglottic stenosis are used to reconstruct three-dimensional geometrical models of the Airway. Computational fluid dynamics is used to obtain Airway Flow patterns during inspiration and expiration in these models. Numerical predictions about Flow velocity, pressure distribution on the Airway lumen, wall shear stress, and Airway resistance are obtained so that the relevance of each individual stenotic level is quantified. Four different virtual surgeries in different combinations are assessed in order to remedy the constricted Airway. The virtual surgery based Airway models are evaluated by comparisons with the pre-treatment Flow modeling results. The predicted numerical data revealed that the removal of the constriction at the level of the vocal folds will have the most significant effect on the Airway resistance. The Flow simulations offer a quantitative method of evaluating the Airway resistance in patients with combined glottic and subglottic stenoses. Predictions of Airway resistances and other numerical calculations from different virtual surgeries give additional inputs for the surgeon, in deciding the most appropriate surgery on a case-by-case basis.
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validation of computational fluid dynamics methodology used for human upper Airway Flow simulations
Journal of Biomechanics, 2009Co-Authors: Goutham Mylavarapu, Shanmugam Murugappan, Mihai Mihaescu, Maninder Kalra, Sid Khosla, Ephraim GutmarkAbstract:An anatomically accurate human upper Airway model was constructed from multiple magnetic resonance imaging axial scans. This model was used to conduct detailed Computational Fluid Dynamics (CFD) simulations during expiration, to investigate the fluid Flow in the Airway regions where obstruction could occur. An identical physical model of the same Airway was built using stereo lithography. Pressure and velocity measurements were conducted in the physical model. Both simulations and experiments were performed at a peak expiratory Flow rate of 200 L/min. Several different numerical approaches within the FLUENT commercial software framework were used in the simulations; unsteady Large Eddy Simulation (LES), steady Reynolds-Averaged Navier-Stokes (RANS) with two-equation turbulence models (i.e. k-epsilon, standard k-omega, and k-omega Shear Stress Transport (SST)) and with one-equation Spalart-Allmaras model. The CFD predictions of the average wall static pressures at different locations along the Airway wall were favorably compared with the experimental data. Among all the approaches, standard k-omega turbulence model resulted in the best agreement with the static pressure measurements, with an average error of approximately 20% over all ports. The highest positive pressures were observed in the retroglossal regions below the epiglottis, while the lowest negative pressures were recorded in the retropalatal region. The latter is a result of the airFlow acceleration in the narrow retropalatal region. The largest pressure drop was observed at the tip of the soft palate. This location has the smallest cross section of the Airway. The good agreement between the computations and the experimental results suggest that CFD simulations can be used to accurately compute aerodynamic Flow characteristics of the upper Airway.
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validation of computational fluid dynamics methodology used for human upper Airway Flow simulations
Journal of Biomechanics, 2009Co-Authors: Goutham Mylavarapu, Shanmugam Murugappan, Mihai Mihaescu, Maninder Kalra, Sid Khosla, Ephraim GutmarkAbstract:Abstract An anatomically accurate human upper Airway model was constructed from multiple magnetic resonance imaging axial scans. This model was used to conduct detailed Computational Fluid Dynamics (CFD) simulations during expiration, to investigate the fluid Flow in the Airway regions where obstruction could occur. An identical physical model of the same Airway was built using stereo lithography. Pressure and velocity measurements were conducted in the physical model. Both simulations and experiments were performed at a peak expiratory Flow rate of 200 L/min. Several different numerical approaches within the FLUENT commercial software framework were used in the simulations; unsteady Large Eddy Simulation (LES), steady Reynolds-Averaged Navier-Stokes (RANS) with two-equation turbulence models (i.e. k − e , standard k − ω , and k − ω Shear Stress Transport (SST)) and with one-equation Spalart–Allmaras model. The CFD predictions of the average wall static pressures at different locations along the Airway wall were favorably compared with the experimental data. Among all the approaches, standard k − ω turbulence model resulted in the best agreement with the static pressure measurements, with an average error of ∼20% over all ports. The highest positive pressures were observed in the retroglossal regions below the epiglottis, while the lowest negative pressures were recorded in the retropalatal region. The latter is a result of the airFlow acceleration in the narrow retropalatal region. The largest pressure drop was observed at the tip of the soft palate. This location has the smallest cross section of the Airway. The good agreement between the computations and the experimental results suggest that CFD simulations can be used to accurately compute aerodynamic Flow characteristics of the upper Airway.