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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.

Virtual implants are represented in bleu, the strategy is to add volume in order to have a distance of approximately 3 mm between the walls.

Air flow velocity

Before virtuals implants

After

Before

0 mm from nostrils
10 mm
20 mm

After

0 mm from nostrils
10 mm
20 mm

Before

30 mm
40 mm

After

30 mm
40 mm

Description and 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 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.
After the virtuals implants we can see a slight increase in velocity in the inferior meatus area especially in the right side. It is a good thing, we can expect more sensation in this zone if the WSS increases too.

Wall Sheer Stress

Before

WSS max 0,2 Pa

After

WSS max 0,2 Pa

Description and analysis

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.
We can see that the floor is greener after virtuals implants which means that the air rubs more on the mucosa.

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 7.9 Pa on the left and 9.2 Pa on the right. The total resistance is around 10,2 Pa which seems in the low average.
After the virtual implants the resistance increase at 11 Pa.

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.
After virtuals implants 53% of the flow passes at the left and 47% at right. So this has reversed and the gap has decreased

Percentage of the airflow in the inferior meatus

Before the virtual implants 42% of the airflow passes throught the inferior meatus and afer 47%. So again the value goes in the right direction, several studies pointed out that one characteristic of ENS is the limited airflow who passes in the inferior meatus.

Cross sectiona area

Before

After

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.
After vitrulas implants the value of the cross sectionnal area is closer to the controle group and more stable throughout the nasal cavity. Which is of course a good thing.

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