Numerical simulation of respiratory flow patterns within human lung

Calay, Rajnish Kaur; Kurujareon, Jutarat; Holdo̸, A. E.

doi:10.1016/s0034-5687(01)00337-1

Cited by 93 publications

(63 citation statements)

References 15 publications

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“…This is related to the assumption made in the study of Calay [2] that the volume distal to respiratory bronchioles is the same throughout the lungs and the change in volume is the same everywhere.…”

Section: Numerical Parametermentioning

confidence: 94%

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Multi-bifurcation flow analysis on 2D human respiratory airway system

Ngali

Osman

Azis

2010

2010 International Conference on Science and Social Research (CSSR 2010)

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Abstract-Drug inhalation through respiratory airway is the principal method in attaining therapeutic effect for many lung diseases. The multi-bifurcating flow structure acquires deep understanding on the flow driven transportation. This work employs Navier-Stokes equation with Splitting Method numerical flow solver utilizing domain characterization technique. Various breathing conditions are commenced to Weibel's morphometric lung model from fifth to seventh generations of human respiratory system. Velocity distributions, vortex formations and cross-sectional velocity profiles are considered for Reynolds number ranging from resting to moderate exercise breathing. Flow with low Reynolds number retains its symmetric cross-sectional velocity profile across each bifurcation region while higher Reynolds number shows the other way. Drug delivery efficacy is higher with slower inhalation while hard breathing stimulates vortex formations and disturbs drug distributions right through the multi-bifurcation structure.

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Section: Numerical Parametermentioning

confidence: 94%

“…To date, studies on symmetric multi-bifurcation flow structures [1][2][3][4] for instance might not represent an actual respiratory structure but had comparable agreements with experimental and theoretical findings.…”

Section: Introductionmentioning

confidence: 91%

Multi-bifurcation flow analysis on 2D human respiratory airway system

Ngali

Osman

Azis

2010

2010 International Conference on Science and Social Research (CSSR 2010)

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“…Hence, the mean free path at the lung temperature is 0.06866 m. The characteristic length of the problem is the main duct diameter; thus, Eq. [3] implies that the Knudsen number has the largest value at distal regions and terminal sacs. According to Weible et al [6], the diameter of the last generation of acinus is 0.29 mm and the corresponding Knudsen number is 0.00046.…”

Section: Boundary Conditionsmentioning

confidence: 99%

“…The present model assumes 15% volumetric expansion ratio, which is identical to that proposed by Tippe and Tsuda [9]. Each ventilatory pattern consists of three characteristic parameters: [1] the tidal volume, [2] the ventilatory rate, and [3] the time relationship between Inhalation and Exhalation (I:E ratio). In normal breathing condition, which is considered for a healthy adult at rest, the tidal volume is about 7 to 9 mL/kg of ideal body weight and the breathing period is 3 sec with the I:E ratio of about 1:2 [16].…”

Section: Wall Motionmentioning

confidence: 99%

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Airflow patterns in a 3D model of the human acinus

2017

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Abstract. Based on the recent photographs of microstructures of an acinus, a novel 3D computational model for air ow and particle transport and deposition was developed. To model the entire acinar region simultaneously, an approach was proposed to reduce the computational space. The air ow was solved using numerical simulations for the cases of expanding and contracting the acinus wall. The volume change of the lung was imposed based on the normal breathing condition with 15% volumetric expansion ratio. Since the entire acinar region was modeled, realistic pressure type boundary conditions were used and the use of earlier unrealistic boundary conditions was avoided. The simulation results showed that the ow patterns in an acinus with moving walls were signi cantly di erent from those in the rigid wall case. Furthermore, due to the asymmetric con guration, the ow patterns were not quite symmetric. It was shown that the ratio of alveolar ow to ductal ow rate controlled the dominant ow regime in each generation. Ratios below 0.005 led to recirculation regime, where ow separation occurred, while values above this threshold led to ows with radial streamlines. In summary, while the ow in the primary generations was characterized by the formation of recirculation regions in the alveoli, the terminal generations were characterized by radial streamlines, which moved towards the alveolar wall. Both ow regimes had substantial e ects on particle deposition in the acinus.

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A novel formulation for Neumann inflow boundary conditions in biomechanics

Gravemeier

Comerford

Yoshihara

et al. 2012

Numer Methods Biomed Eng

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Neumann boundary conditions prescribing the total momentum flux at inflow boundaries of biomechanical problems are proposed in this study. This approach enables the simultaneous application of velocity/flow rate and pressure curves at inflow boundaries. As the basic numerical method, a residual-based variational multiscale (or stabilized) finite element method is presented. The focus of the numerical examples in this work is on respiratory flows with complete flow reversals. However, the proposed formulation is just as well suited for cardiovascular flow problems with partial retrograde flow. Instabilities, which were reported for such problems in the literature, are resolved by the present approach without requiring the additional consideration of a Lagrange multiplier technique. The suitability of the approach is demonstrated for two respiratory flow examples, a rather simple tube and complex tracheobronchial airways (up to the fourth generation, segmented from end-expiratory CT images). For the latter example, the boundary conditions are generated from mechanical ventilation data obtained from an intensive care unit patient suffering from acute lung injury. For the tube, analytical pressure profiles can be replicated, and for the tracheobronchial airways, a correct distribution of the prescribed total momentum flux at the inflow boundary into velocity and pressure part is observed.

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Numerical simulation of respiratory flow patterns within human lung

Cited by 93 publications

References 15 publications

Multi-bifurcation flow analysis on 2D human respiratory airway system

Multi-bifurcation flow analysis on 2D human respiratory airway system

Airflow patterns in a 3D model of the human acinus

A novel formulation for Neumann inflow boundary conditions in biomechanics

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