Numerical analysis of stochastic dispersion of micro-particles in turbulent flows in a realistic model of human nasal/upper airway

Ghahramani, Ebrahim; Abouali, Omid; Emdad, Homayoun; Ahmadi, Goodarz

doi:10.1016/j.jaerosci.2013.09.004

Cited by 63 publications

(44 citation statements)

References 52 publications

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“…On the other hand, the LRN k-ω model with an appropriate damping function appears to be capable of reproducing the behavior of laminar, transitional and fully turbulent flow in complex 3D constricted geometry. However, Ghahramani et al (2014) claim that the LRN k-ε model performs better than the LRN k-ω model when comparing the mean flow velocities and turbulence intensity in the centerline of a converging/diverging nozzle. Pollard et al (2012) provide an overview of the methods and the cautious interplay between simulations and experiments as well as the interdependency of outlet/inlet conditions.…”

Section: Turbulence Modelmentioning

confidence: 97%

“…Later Zhang and Kleinstreuer (2011) concluded that the best agreement with the experiments performed by Johnstone et al (2004) was obtained when using the SST k-ω model. However, Ghahramani et al (2014) used the LRN k-ω and the LRN k-ε model for the realistic nasal/upper airway. They claimed that between the two equation turbulence models, the LRN k-ε model was more appropriate for the simple transitional flow in a convergingdiverging nozzle model of the glottis area.…”

Section: Introductionmentioning

confidence: 99%

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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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Section: Turbulence Modelmentioning

confidence: 97%

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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“…and Ball et al, Ghahramani et al [8] used a realistic model to perform a numerical analysis in the upper human airway. Saksono et al [9] and Lin et al.…”

Section: Doorly Et Almentioning

confidence: 99%

Large-scale CFD simulations of the transitional and turbulent regime for the large human airways during rapid inhalation

Calmet

Gambaruto

Bates

et al. 2016

Computers in Biology and Medicine

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The dynamics of unsteady flow in the human large airways during a rapid inhalation were investigated using highly detailed large-scale computational fluid dynamics on a subject-specific geometry. The simulations were performed to resolve all the spatial and temporal scales of the flow, thanks to the use of massive computational resources. A highly parallel finite element code was used, running on two supercomputers, solving the transient incompressible Navier-Stokes equations on unstructured meshes. Given that the finest mesh contained 350 million elements, the study sets a precedent for large-scale simulations of the respiratory system, proposing an analysis strategy for mean flow, fluctuations and wall shear stresses on a rapid and short inhalation (a so-called sniff). The geometry used encompasses the exterior face and the airways from the nasal cavity,

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“…The first numerical studies of the airflow pattern in the nasal airway were accomplished by Keyhani et al [20] and Subramaniam et al [21]. Recently, particle dispersion and deposition have been studied in realistic nasal airways [22,23,24]. These simulations were performed with the commercial software packages CFX [22] and Fluent [23,24].…”

Section: Introductionmentioning

confidence: 99%

“…Recently, particle dispersion and deposition have been studied in realistic nasal airways [22,23,24]. These simulations were performed with the commercial software packages CFX [22] and Fluent [23,24]. Most of the research in this area considers a steady inlet airflow [25] or an unsteady flow representing inhalation-exhalation cycles [26].…”

Section: Introductionmentioning

confidence: 99%

Numerical Simulation of the Dispersion and Deposition of a Spray Carried by a Pulsating Airflow in a Patient-Specific Human Nasal Cavity

Farnoud

Cui

Baumann

et al. 2017

Proceedings ILASS–Europe 2017. 28th Conference on Liquid Atomization and Spray Systems

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The present numerical study concerns the dispersion and deposition of a nasal spray in a patient-specific human nose. The realistic three-dimensional geometry of the nasal cavity is reconstructed from computer tomography (CT) scans. Identification of the region of interest, removal of artifacts, segmentation, generation of the .STL file and the triangulated surface grid are performed using the software packages ImageJ, meshLab, and NeuRA2. An unstructured computational volume grid with approximately 15 million tetrahedral grid cells is generated using the software Ansys ICEM-CFD 11.0. An unsteady Eulerian-Lagrangian formulation is used to describe the airflow and the spray dispersion and deposition in the realistic human nasal airway using two-way coupling. A new solver called pimpleParcelFoam is developed, which combines the lagrangianParcel libraries with the pimpleFoam solver within the software package OpenFOAM 3.0.0. A large eddy simulation (LES) with the dynamic sub-grid scale (SGS) model is performed to study the spray in both a steady and a pulsating airflow with an inflow rate of 7.5 L/min (or maximum value in case of the pulsating spray) and a frequency of 45 Hz for pulsation as used in commercial inhalation devices. 10,000 mono-disperse particles with the diameters of 2.4 µm and 10 µm are uniformly injected at the nostrils. In order to fulfil the stability conditions for the numerical solution, a constant time-step of 10 −5 s is implemented. The simulations are performed for a real process time of 1 s, since after the first second of the process, all particles have escaped through the pharynx or they are deposited at the surface of the nasal cavity. The numerical computations are performed on the high-performance computer bwForCluster MLS&WISO Production using 256 processors, which take around 32 and 75 hours for steady and pulsating flow simulation, respectively. The study shows that the airflow velocity reaches its maximum values in the nasal valve, in parts of the septum and in the nasopharynx. A complex airflow is observed in the vestibule and in the nasopharynx region, which may directly affect the dispersion and deposition pattern of the spray. The results reveal that the spray tends to deposit in the nasal valve, the septum and in the nasopharynx due to the change in the direction of the airflow in these regions. Moreover, it is found that due to the pulsating airflow, the aerosols are more dispersed and penetrate deeper into the posterior regions and the meatuses where the connections to the sinuses reside.

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Numerical analysis of stochastic dispersion of micro-particles in turbulent flows in a realistic model of human nasal/upper airway

Cited by 63 publications

References 52 publications

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

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

Large-scale CFD simulations of the transitional and turbulent regime for the large human airways during rapid inhalation

Numerical Simulation of the Dispersion and Deposition of a Spray Carried by a Pulsating Airflow in a Patient-Specific Human Nasal Cavity

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