Fluid simulation
Introduction
Author: Aurélien RUMIANO
Patient: Dang Tung
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
The middle turbinates are absent, and the inferior turbinates are cut by 80%.
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 concentrated in the middle meatus. It is faster on the left side (right side on the illustration) than on the right side.
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.
Airflow imbalance
66% of the airflow passes through the right side and therefore 34% 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 4.8 Pa which is low. This is due to the lack of volume. There is more nasal resistance on the left side than on the right, 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 above 600 mm² from 20 mm to nostrils. Which is very 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 absence of middle turbinates and the nearly entirely removed inferior turbinates result in airflow being concentrated in the middle 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, likely caused by a difference in the size of the nasal vestibule openings.
Large implants in the inferior meatus along the lateral walls could be beneficial.