Numerical investigation of nasal airflow: comparative analysis of before and after surgery states for an obstructed nasal cavity

Date

2024-1-15

Author

Güneş, Gökberk

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The nasal cavity is a multi-functional but convoluted, diverse, and dynamic structure located within the body. These chaotic characteristics make conducting the traditional research methods challenging. Consequently, the paradigm in breathing-related research shifts towards computer-centric numerical methods. In this thesis, numerical simulations are conducted on a nasal cavity both before and after surgery for an individual with nasal obstruction. The investigation is conducted using identical discharge levels for both geometries, corresponding to restful and quick breathing rates. Furthermore, only free and open-source software are used to enhance availability and reproducibility. The most noteworthy one, OpenFOAM, is employed to solve numerical simulations and generate volumetric meshes. The turbulence in the airflow is simulated by resolving the large eddies and modeling the small ones with the WALE model. Multiple parameters are controlled to interpret the results: pressure drops, discharge rates, nasal resistance values, turbulent kinetic energy levels, localized discharge rates, localized wall shear stress values. The results show that even though the nasal surgery increases cross-sectional areas, stimulation on the mechano- and thermo- receptors does not decrease; instead, it evolves into a homogeneous state throughout the cavity. This result suggests better overall stimulation of receptors; hence, a lesser nasal obstruction feeling. The verification of grid resolution for the LES is performed using Celik indices. Similarly, time resolution is verified by comparing Kolmogorov time scale to the selected time steps. Lastly, the results are partially validated through a comparison of nasal resistance values with the existing literature.

Subject Keywords

Breathing, LES, WALE, OpenFOAM, Nasal cavity

URI

https://hdl.handle.net/11511/108224

Collections

Graduate School of Natural and Applied Sciences, Thesis