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Do you smell what I smell? How nasal geometry affects airflow dynamics

Recent work between the CFD group of Assoc. Prof. Kiao Inthavong of RMIT, Prof. David F. Fletcher of the University of Sydney and Dr. Narinder Singh a specialist Ear, Nose and Throat surgeon at Westmead hospital used the novel SBES scale resolving model in Ansys Fluent to study flow in the nasal passage and to validate the computations against new experimental data. This work was chosen as the featured article in Physics of Fluids for the January 2021 issue. During the COVID pandemic there have been many papers on the spread and control of aerosols post sneezing. This work addresses the flow within the nose and demonstrates that as the flow rate is increased it changes from steady laminar to an unsteady laminar flow with pockets of turbulence that are well captured using the SBES model.

Scanned data were imported into Ansys SpaceClaim and the geometry was prepared for meshing. Images of the geometry are given in Fig. 1 below.

Fig. 1: The computational geometry (reproduced from the article).

Then meshing was performed using the new mosaic method with the poly-hexcore meshing technology that allows a high quality mesh that has hexes in the bulk of the domain, inflation at the walls which are connected via polyhedra. The finest mesh had 11.8 million nodes which was generated very efficiently using the parallel meshing option. Fig. 2 shows a section of the mesh in a narrow region. The highly uniform mesh size away from the walls is ideal for the LES model used in the bulk.

Fig. 2 Images of the mesh (taken from the article)

Fig. 3 below shows instantaneous velocities on a number of planes through the model. Local regions of high instantaneous velocity and therefore turbulence generation are evident.

Fig. 3 Instantaneous velocity magnitude (taken from the article).

If you are interested to learn more about the technology used, SBES turbulence modelling or flow in the nose, this paper is a great read and we highly recommend it. The article is freely available via this link until 14 February 2021 or contact Prof. David Fletcher directly (david.fletcher@sydney.edu.au) for a preprint.

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