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09/02/12 Meeting Minutes



The transition period of the split (bifurcation) may change the conditions further down

Asked Dr. Chung what which outlet condition should be used in the matlab model

Dr. Chung said we should research this in fluids textbooks: miner loss

Tom then talked about the effect of the branches curving

This means that the vector gives a different angle change than the one that is at the bifurcation point.

Adrian: Are you assuming that the angle changes are symmetrical?

Charlie: We can gain some useful information from the start and end point data

However, our model will build in innacuracies for curved pipes as the length will be different

Charlie: The matlab model can accept angle changes and work out the resistance from this

However at the moment it is just accepting standard angles

Tom’s next step is to get the angle change data from the centreline file

This will be a challenge to code, however

Dr Chung: Maybe we need length and diameter from

Tom: Can optimise the code so that the conditions are updated to an end point

Dr. Chung: need to read the angle change paper very carefully

Just as Tom left Talha made it clear that the bernouilli needs to apply for the straight sections of pipe, and the angle formula calculates the resistance of the bifurcation


Getting the program to iterate more than once

Surface plotting isnt working

The other big thing is getting the realistic boundary conditions

Tom says he has a macro file that can get the surface of the lungs into a point cloud


Will look into ‘miner’ loss

The recoil pressure isnt needed as Tom already considered the elasticity in the alveoli

The elasticity of the airways is what Daniel needs to look for




Has been looking at the trachea, messing around with the mesh parameters

They don’t seem to settle

Final number of elements: 800,000

It reaches a point where it doesn’t allow any further meshing

Dr. Chung: what was your last base size: 1, if you use 0.5 it doesn’t change? No

The graphs for the trachea aren’t settling as expected

Adrian thinks the range is exacerbating it



Finished the grid independence test for the upper airways

Base size: 0.5mm, prism layers, 10 layers

Dr. Chung: what region does the prism layers cover: 200%

Dr. Chung: what was the smallest base size you tried: 0.5

Dr. Chung: maybe you could reduce the base size a bit: i.e. 0.2 and 0.1

Sounds very good that wall shear settled down, as it is a very sensitive property

Using K-epsilon flow turbulence


Dr Chung got the jet from Laura on Sunday: fantastic

Laura has started looking back at the particles again

Done a simulation for the medium sized upper airway

Trying to get numerical data out of her simulation rather than a simple particle line plot

However Laura is getting the simulation crashing quite a lot

Tom: Maybe its because your graphics card isn’t keeping up with it

Laura was using 1micrometer sized particles, at a constant density

Dr. Chung: need to find out the typical mass of inhaler particles being used

Need to find out what happens when they hit the wall

To use a stick condition Laura needs to use unsteady simulations

Ending Conversation

Dr. Chung: 1D team need to meet with talha to talk about bernouilli

3D team need to meet individually or separately

Dr. Chung: Start working on the technical report documentation, so that before every meeting we can talk about it.

Business plan: doesn’t exist this year, only in executive summary, so there is much less emphasis on this

Peer marking: Will do this at the end of the term or later