Best Practice Advice AC7-02: Difference between revisions
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Briefly describe the key fluid physics/flow regimes which exert an influence on the DOAPs. Ideally this should draw together into a coherent picture the associated UFR descriptions together with any important interactions which are AC specific. Mention the UFRs associated with this AC that you have considered in drafting your best practice advice. ''Access the Knowledge Base to find the UFRs associated with your AC''. | Briefly describe the key fluid physics/flow regimes which exert an influence on the DOAPs. Ideally this should draw together into a coherent picture the associated UFR descriptions together with any important interactions which are AC specific. Mention the UFRs associated with this AC that you have considered in drafting your best practice advice. ''Access the Knowledge Base to find the UFRs associated with your AC''. | ||
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In the present AC, experiments and simulations were conducted at a flowrate of 60 L/min through an upper airway geometry. | |||
At this flow conditions, the Reynolds number for air in the trachea is 4920, which is well within the turbulent regime. | |||
Geometric effects, such as the bent in the oropharyngeal region and the constriction at the laryngeal glottis (just upstream of the trachea, see fig. 25) enhance turbulence levels as the air moves from the inlet to the region of the trachea. | |||
Turbulent kinetic energy levels reach a peak in the shear layer formed between the high speed laryngeal jet and the surrounding (low speed) air (see fig. 25). | |||
The characteristics of the laryngeal jet formation bear a resemblance to the flow through a constricted pipe, which can be classified as a free shear flow where the wall serves to confine the spreading of the jet rather than producing turbulence (Tawhai & Lin, 2011). | |||
High turbulence levels persist in the region of the first bifurcation (stations H1-H2 & J1-J2 in fig. 12(b)). | |||
==Application Uncertainties== | ==Application Uncertainties== | ||
Revision as of 10:40, 21 May 2020
Airflow in the human upper airways
Application Challenge AC7-02 © copyright ERCOFTAC 2020
Best Practice Advice
Key Fluid Physics
In the present AC, experiments and simulations were conducted at a flowrate of 60 L/min through an upper airway geometry. At this flow conditions, the Reynolds number for air in the trachea is 4920, which is well within the turbulent regime. Geometric effects, such as the bent in the oropharyngeal region and the constriction at the laryngeal glottis (just upstream of the trachea, see fig. 25) enhance turbulence levels as the air moves from the inlet to the region of the trachea. Turbulent kinetic energy levels reach a peak in the shear layer formed between the high speed laryngeal jet and the surrounding (low speed) air (see fig. 25). The characteristics of the laryngeal jet formation bear a resemblance to the flow through a constricted pipe, which can be classified as a free shear flow where the wall serves to confine the spreading of the jet rather than producing turbulence (Tawhai & Lin, 2011). High turbulence levels persist in the region of the first bifurcation (stations H1-H2 & J1-J2 in fig. 12(b)).
Application Uncertainties
Computational Domain and Boundary Conditions
Discretisation and Grid Resolution
Turbulence Models
Recommendations for Future Work
Acknowledgements
References
Armenio, V., Piomelli, U. & Fiorotto, V. 1999
- Effect of the subgrid scales on particle motion. Physics of Fluids 11 (10), 3030 – 3042.
etc
Contributed by: P. Koullapisa, J. Muelab, O. Lehmkuhlc, F. Lizald, J. Jedelskyd, M. Jichad, T. Jankee, K. Bauere, M. Sommerfeldf, S. C. Kassinosa —
aDepartment of Mechanical and Manufacturing Engineering, University of Cyprus, Nicosia, Cyprus
bHeat and Mass Transfer Technological Centre, Universitat Politècnica de Catalunya, Terrassa, Spain
cBarcelona Supercomputing center, Barcelona, Spain
dFaculty of Mechanical Engineering, Brno University of Technology, Brno, Czech Republic
eInstitute of Mechanics and Fluid Dynamics, TU Bergakademie Freiberg, Freiberg, Germany
fInstitute Process Engineering, Otto von Guericke University, Halle (Saale), Germany
© copyright ERCOFTAC 2020