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Fluid simulation

Introduction

Author: Aurélien RUMIANO

Patient: Aurélien RUMIANO

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.

3d model

CT-SCAN

Right side: We can see that the right turbinate is almost completely cuted, just a little bit of the head remains. In red it is a cartilage implant mostly positionned in the anterior part.
Left side: On the left side we can say that around 50% of the left turbinate is missing.

We can also see that the septum is still twisted despite septoplasty. The right middle turbinate is almost absent due to the twisted nasal septum which has compressed it.

Airflow velocity

0 mm from nostrils
10 mm
20 mm
30 mm
40 mm

Description

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 majority of airflow passes through the middle meatus.
The maximum air velocity is reached in the anterior part.
Turbulence is present in the inferior meatus.

Analysis

The flow of air which passes mainly through the middle meatus is apparently a characteristic of ENS. The airflow velocity is a little higher in the lower meatus in the right side compared to the left side due to the cartilage implant.
In the red zone the airflow is accelerated due to a section restriction, so no volume should be added to this zone.

Wall Sheer Stress

WSS max 0,2 Pa

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.

Analysis

We can see that the areas where the WSS is the highest are mainly the anterior part and to a lesser extent the middle meatus. This is not surprising given that there is almost no airflow into the inferior meatus.

Nasal resistance

Description et analyse

The right nostril is more colored than the left, this means that the pressure loss is higher on the right than on the left. However the imbalance is quite low. The total resistance is around 10 Pa which is considered at the limit of the normal values.. According to my little experience in fluid simulation, values between 10 and 20 Pa are normal.

Air flow imbalance

44% of the flow passes to the left and therefore 56% to the right.
There is a small flow imbalance but in my opinion it is not problematic. This imbalance may only be due to the nasal cycle.

Cross sectiona area

The further away from the nostrils, the bigger the cross sectional area is. It is of course the consequence of the turbinectomy. The section is stabilised at around 350 mm² which is around 100mm² bigger than the control group.

Conclusion

A lot of volume is missing on the right in the middle and posterior part. The cartilage implant only added volume in the anterior part. On the left there is also a lack of volume all along, especially between the turbinate and the floor. Most of the airflow passes through the middle meat, the airflow imbalance is normal. Oddly, despite the lack of volume quantified by the anomalous cross sectional area, the nasal resistance is at the limit of normal.

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