Flow and air conditioning simulations of computer turbinectomized nose models

Abstract

Air conditioning for the human respiratory system is the most important function of the nose. When obstruction occurs in the nasal airway, turbinectomy is used to correct such pathology. However, mucosal atrophy may occur sometime after this surgery when it is overdone. There is not enough information about long-term recovery of nasal air conditioning performance after partial or total surgery. The purpose of this research was to assess if, based on the flow and temperature/humidity characteristics of the air intake to the choana, partial resection of turbinates is better than total resection. A normal nasal cavity geometry was digitized from tomographic scans and a model was printed in 3D. Dynamic (sinusoidal) laboratory tests and computer simulations of airflow were conducted with full agreement between numerical and experimental results. Computational adaptations were subsequently performed to represent six turbinectomy variations and a swollen nasal cavity case. Streamlines along the nasal cavity and temperature and humidity distributions at the choana indicated that the middle turbinate partial resection is the best alternative. These findings may facilitate the diagnosis of nasal obstruction and can be useful both to plan a turbinectomy and to reduce postoperative discomfort.

Glossary

Δp

Pressure difference between nostril and choana (Pa)

Δp _pipe

Pressure drop for Poiseuille flow (Pa)

Δz

Distance between pressure ports for Poiseuille flow (m)

ϕ

Relative humidity

μ

Air dynamic viscosity (kg m⁻¹s⁻¹)

ρ

Air density (kg/m³)

ω _r

Respiratory frequency (rad/s)

$\dot{m}$

Boundary condition mass flow rate (kg/s)

${\dot{m}}_e$

Experimental mass flow rate (kg/s)

a, b

Empirical constants

${c}_{H_2O}$

Water vapor concentration in air $\left({\mathrm{kg}}_{{\mathrm{H}}_2\mathrm{O}}/{\mathrm{kg}}_{\mathrm{humid}\kern0.24em \mathrm{air}}\right)$

c _p

Air specific heat at constant pressure (J kg⁻¹K⁻¹)

A _pipe

Cross-sectional area for Poiseuille flow (m²)

D

Diffusivity of water vapor in air (m²/s)

D _P

Piston diameter (m)

k

Air thermal conductivity (W m⁻¹K⁻¹)

L

Piston travel length (m)

MF _vapour

Water vapor mass fraction $\left({\mathrm{kg}}_{{\mathrm{H}}_2\mathrm{O}}/{\mathrm{kg}}_{\mathrm{humid}\kern0.24em \mathrm{air}}\right)$

p

Pressure (Pa)

p _sat

Saturation pressure (Pa)

Q

Volume flow (m³/s)

T

Temperature (K)

t

Time (s)

U

Velocity vector (m/s)

v

Air kinematic viscosity m²/s