Fluid simulation

Introduction

Author: Aurélien RUMIANO

Patient: Modele

Parameters of the study

Flow used for the fluid study 15l/min.
Inspiration phase.
Humidity and temperature are not taken into account.

🛑Disclaimer: I am neither a fluid mechanics researcher nor a doctor. The results I obtain using my fluid simulation software may be approximate. The purpose of these fluid simulations is to give you an idea of the air flow and possible problems related to it.

The illustration below represents the nasal cavity, the anterior part in red, the middle meatus in green and finally the inferior meatus in blue.

The following illustration represents the negative of the nasal cavity, that is to say the air which is inside the nasal cavity. All illustrations that follow will be represented in this manner.

The block that sticks the nostrils simply represents the air around it.

CT-SCAN

Only part of the lower turbinates heads remain.

Airflow velocity

Description & analysis

The current lines represent the air flow, the speed scale goes from 0 to 2.5 m/s.
Speeds above 2.5 m/s are shown in red.
The airflow is clearly concentrated in the lower meatus due to the emptiness left by the absence of the inferior turbinates.

Wall Sheer Stress

Description

The areas colored red represent areas where the WSS is greater than 0.2 Pa. That is to say, these are the areas where the air rubs the most against the mucosa and therefore creates the most air sensation.

We can see that the areas where the WSS is the highest are mainly the anterior part. This is a normal phenomenon because this is where the section is the smallest.
The WSS is low at the floor of the nasal cavity. And we can see less WSS zone at right due to the airflow imbalance between the two sides.

Airflow imbalance

33% of the airflow passes through the right side and therefore 67% on the left.
So the airflow is not well balanced between the two sides. Enough to cause discomfort.

Nasal resistance

Description and analysis

The total resistance is around 8 Pa which is quite low. This is due to the lack of volume. There is more nasal resistance on the right side than on the left, which creates an airflow imbalance between the two sides. According to my little experience in fluid simulation, values between 10 and 20 Pa are normal.

Cross sectiona area

The cross-sectional area peak at nearly 400 mm² from 20 mm to nostrils. Which is high.
The data of the control group are pulled from a study, but I have seen some non ENS case at around 300mm². So I think that between 200 and 300 mm² the values can be considered normal.

Conclusion

There is a significant lack of volume. The near absence of inferior turbinates result in airflow being concentrated in the inferior meatus, a general reduction in WSS throughout the nasal cavity, and decreased overall nasal resistance.
There is also an airflow imbalance between the left and right sides.
Large implants in the inferior meatus along the lateral walls could be beneficial.