Numerical investigation of turbulent airflow and microparticle deposition in a realistic model of human upper airway using LES

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

doi:10.1016/j.compfluid.2017.08.003

Cited by 29 publications

(11 citation statements)

References 38 publications

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“…Fig 8 shows good agreement between the simulation performed by the present code (Alya) and the numerical results of [47, 49, 63]. Differences in deposition results are due to the coarser airway surfaces in the replica producing higher deposition efficiencies than the numerical model, already observed frequently in literature, see [64, 65] who provide an extended study which can be summarized as the “wall roughness region enhanced particle capturing effect” or other study [66] who compared deposition of different level of surface roughness replicas (see Fig 8 Model A,B,C) from [61] with LES simulations.…”

Section: Methodssupporting

confidence: 75%

Nasal sprayed particle deposition in a human nasal cavity under different inhalation conditions

et al. 2019

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Deposition of polydisperse particles representing nasal spray application in a human nasal cavity was performed under transient breathing profiles of sniffing, constant flow, and breath hold. The LES turbulence model was used to describe the fluid phase. Particles were introduced into the flow field with initial spray conditions, including spray cone angle, insertion angle, and initial velocity. Since nasal spray atomizer design determines the particle conditions, fifteen particle size distributions were used, each defined by a log-normal distribution with a different volume mean diameter ( Dv 50). Particle deposition in the anterior region was approximately 80% when Dv 50 > 50μm, and this decreased to 45% as Dv 50 decreased to 10μ m for constant and sniff breathing conditions. The decrease in anterior deposition was countered with increased deposition in the middle and posterior regions. The significance of increased deposition in the middle region for drug delivery shows there is potential for nasal delivered drugs to reach the highly vascularised mucosal walls in the main nasal passages. For multiple targeted deposition sites, an optimisation equation was introduced where deposition results of any two targeted sites could be combined and a weighting between 0 to 1 was applied to each targeted site, representing the relative importance of each deposition site.

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Section: Methodssupporting

confidence: 75%

Nasal sprayed particle deposition in a human nasal cavity under different inhalation conditions

et al. 2019

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“…The corresponding run-time for a RANS simulation was ∼ 12 hours; for an LES computation, it was 4–5 days. Note that for the LES work, the simulated flow interval was 0.5 second for the 30 L/min case, with 0.0002 second as the time-step 37 and it was 0.25 second for the 55 and 85 L/min flow rates with the time-step at 0.0001 second. In the computations, assumed air density was 1.204 kg/m 3 and 1.825×10 − 5 kg/m.s was used as dynamic viscosity of air.…”

Section: Methodsmentioning

confidence: 99%

Exposure to a COVID-19 carrier: transmission trends in respiratory tract and estimation of infectious dose

Basu

2020

Preprint

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How human respiratory physiology and inhaled airflow therein proceed to impact transmission of SARS-CoV-2, leading to the initial infection, is an open question. An answer can help determine the susceptibility of an individual on exposure to a COVID-2019 carrier and can also quantify the still-unknown infectious dose for the disease. Combining computational fluid mechanics-based tracking of respiratory transport in anatomic domains with sputum assessment data from hospitalized COVID-19 patients and earlier measurements of ejecta size distribution during regular speech - this study shows that the regional deposition of virus-laden inhaled droplets at the initial nasopharyngeal infection sites, located in the upper airway, peaks over the droplet size range of 2.5 - 19 microns; and reveals that the number of virions that can potentially establish the infection is, at most, of O(100).

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“…11 shows good agreement between the simulation performed by the present code (Alya) and the numerical results of ( Schroeter et al, 2011 , Shang et al, 2015 , Shi et al, 2007 ). Differences in deposition results are due to the coarser airway surfaces in the replica producing higher deposition efficiencies than the numerical model, already observed frequently in literature, see Bahmanzadeh, Abouali, Faramarzi, and Ahmadi (2015) and Shi et al (2007) who provide an extended study which can be summarized as the “wall roughness region enhanced particle capturing effect” or other study ( Ghahramani, Abouali, Emdad, & Ahmadi, 2017 ) who compared deposition of different level of surface roughness replicas (see Fig. 11 Model A,B,C) from Kelly, Asgharian, Kimbell, and Wong (2004) with LES simulations.…”

Section: Governing Equationsmentioning

confidence: 94%

Computational modelling of an aerosol extraction device for use in COVID-19 surgical tracheotomy

Calmet

Bertomeu

McIntyre

et al. 2022

Journal of Aerosol Science

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In view of the ongoing COVID-19 pandemic and its effects on global health, understanding and accurately modelling the propagation of human biological aerosols has become crucial. Worldwide, health professionals have been one of the most affected demographics, representing approximately 20% of all cases in Spain, 10% in Italy and 4% in China and US. Methods to contain and remove potentially infected aerosols during Aerosol Generating Procedures (AGPs) near source offer advantages in reducing the contamination of protective clothing and the surrounding theatre equipment and space. In this work we describe the application of computational fluid dynamics in assessing the performance of a prototype extraction hood as a means to contain a high speed aerosol jet. Whilst the particular prototype device is intended to be used during tracheotomies, which are increasingly common in the wake of COVID-19, the underlying physics can be adapted to design similar machines for other AGPs. Computational modelling aspect of this study was largely carried out by Barcelona Supercomputing Center using the high performance computational mechanics code Alya. Based on the high fidelity LES coupled with Lagrangian frameworks the results demonstrate high containment efficiency of generated particles is feasible with achievable air extraction rates.

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Numerical investigation of turbulent airflow and microparticle deposition in a realistic model of human upper airway using LES

Cited by 29 publications

References 38 publications

Nasal sprayed particle deposition in a human nasal cavity under different inhalation conditions

Nasal sprayed particle deposition in a human nasal cavity under different inhalation conditions

Exposure to a COVID-19 carrier: transmission trends in respiratory tract and estimation of infectious dose

Computational modelling of an aerosol extraction device for use in COVID-19 surgical tracheotomy

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