On locating the obstruction in the upper airway via numerical simulation

Wang, Yueshe; Elghobashi, S.

doi:10.1016/j.resp.2013.12.009

Cited by 46 publications

(33 citation statements)

References 34 publications

(47 reference statements)

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“…Direct numerical simulation (DNS) does not require any turbulence models to resolve turbulent fluctuations if the time and length scales used are small enough and is often considered as the gold standard in numerical simulations. However, the high computational cost limits its applications, and very limited studies can be found in the literature for both simplified geometries (Lin et al, 2007; Varghese et al, 2007) and human nasal cavity (Wang and Elghobashi, 2014). …”

Section: Introductionmentioning

confidence: 99%

Computational modeling and validation of human nasal airflow under various breathing conditions

Jiang

Dong

et al. 2017

Journal of Biomechanics

131

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The human nose serves vital physiological functions, including warming, filtration, humidification, and olfaction. These functions are based on transport phenomena that depend on nasal airflow patterns and turbulence. Accurate prediction of these airflow properties requires careful selection of computational fluid dynamics models and rigorous validation. The validation studies in the past have been limited by poor representations of the complex nasal geometry, lack of detailed airflow comparisons, and restricted ranges of flow rate. The objective of this study is to validate various numerical methods based on an anatomically accurate nasal model against published experimentally measured data under breathing flow rates from 180 to 1100 ml/s. The numerical results of velocity profiles and turbulence intensities were obtained using the laminar model, four widely used Reynolds-averaged Navier-Stokes (RANS) turbulence models (i.e., k- , standard k- Shear Stress Transport k- , and Reynolds Stress Model), large eddy simulation (LES) model, and direct numerical simulation (DNS). It was found that, despite certain irregularity in the flow field, the laminar model achieved good agreement with experimental results under restful breathing condition (180 ml/s) and performed better than the RANS models. As the breathing flow rate increased, the RANS models achieved more accurate predictions but still performed worse than LES and DNS. As expected, LES and DNS can provide accurate predictions of the nasal airflow under all flow conditions but have an approximately 100-fold higher computational cost. Among all the RANS models tested, the standard k- model agrees most closely with the experimental values in terms of velocity profile and turbulence intensity.

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Section: Introductionmentioning

confidence: 99%

Computational modeling and validation of human nasal airflow under various breathing conditions

Jiang

Dong

et al. 2017

Journal of Biomechanics

131

View full text Add to dashboard Cite

show abstract

“…The number of control volumes for this case was 148 million. Recently, Wang and Elghobashi (2014) have solved the nose cavity with a short upper part of the trachea and with a very limited length of the laryngeal jet using the DNS-lattice Boltzmann. They solved steady inflow and outflow (not the breathing cycle) and the model contained 208 million voxels.…”

Section: Introductionmentioning

confidence: 99%

Numerical investigation of inspiratory airflow in a realistic model of the human tracheobronchial airways and a comparison with experimental results

Elcner

Lízal

Jedelský

et al. 2015

Biomech Model Mechanobiol

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In this article, the results of numerical simulations using computational fluid dynamics (CFD) and a comparison with experiments performed with phase Doppler anemometry are presented. The simulations and experiments were conducted in a realistic model of the human airways, which comprised the throat, trachea and tracheobronchial tree up to the fourth generation. A full inspiration/expiration breathing cycle was used with tidal volumes 0.5 and 1 L, which correspond to a sedentary regime and deep breath, respectively. The length of the entire breathing cycle was 4 s, with inspiration and expiration each lasting 2 s. As a boundary condition for the CFD simulations, experimentally obtained flow rate distribution in 10 terminal airways was used with zero pressure resistance at the throat inlet. CCM+ CFD code (Adapco) was used with an SST k-ω low-Reynolds Number RANS model. The total number of polyhedral control volumes was 2.6 million with a time step of 0.001 s. Comparisons were made at several points in eight cross sections selected according to experiments in the trachea and the left and right bronchi. The results agree well with experiments involving the oscillation (temporal relocation) of flow structures in the majority of the cross sections and individual local positions. Velocity field simulation in several cross sections shows a very unstable flow field, which originates in the tracheal laryngeal jet and propagates far downstream with the formation of separation zones in both left and right airways. The RANS simulation agrees with the experiments in almost all the cross sections and shows unstable local flow structures and a quantitatively acceptable solution for the time-averaged flow field.

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“…Computational fluid dynamics (CFD) was performed on the 3D surface model using previously described methods20. Briefly, CFD results were calculated using a custom developed 3-dimensional solver based on the direct numerical simulation lattice Boltzmann methods (DNS-LBM).…”

Section: Resultsmentioning

confidence: 99%

“…The imaging probe incorporated a position sensor to record the location of each cross-sectional scan, which is crucial for the generation of three dimensional models of the complex upper airway shape. Using these structural models, computational simulations can be performed to provide physicians a better understanding of airflow within the upper airway19202122. The first high speed in vivo imaging of human upper airway with integrated position tracking was demonstrated.…”

mentioning

confidence: 99%

Anatomically correct visualization of the human upper airway using a high-speed long range optical coherence tomography system with an integrated positioning sensor

Jing

Chou

et al. 2016

Sci Rep

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The upper airway is a complex tissue structure that is prone to collapse. Current methods for studying airway obstruction are inadequate in safety, cost, or availability, such as CT or MRI, or only provide localized qualitative information such as flexible endoscopy. Long range optical coherence tomography (OCT) has been used to visualize the human airway in vivo, however the limited imaging range has prevented full delineation of the various shapes and sizes of the lumen. We present a new long range OCT system that integrates high speed imaging with a real-time position tracker to allow for the acquisition of an accurate 3D anatomical structure in vivo. The new system can achieve an imaging range of 30 mm at a frame rate of 200 Hz. The system is capable of generating a rapid and complete visualization and quantification of the airway, which can then be used in computational simulations to determine obstruction sites.

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On locating the obstruction in the upper airway via numerical simulation

Cited by 46 publications

References 34 publications

Computational modeling and validation of human nasal airflow under various breathing conditions

Computational modeling and validation of human nasal airflow under various breathing conditions

Numerical investigation of inspiratory airflow in a realistic model of the human tracheobronchial airways and a comparison with experimental results

Anatomically correct visualization of the human upper airway using a high-speed long range optical coherence tomography system with an integrated positioning sensor

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