Query: How to make Turbulence smoke / fire expand and fill an entire internal region

Hi peeps
So I’m making a ‘‘breathing lungs’’ animation with Turbulence (representing the airflow).
You can see it here…

The thing I’m having trouble with… As the oxygen enters INTO the lungs, I really want it to expand and fill ALL of the internal tunnels, but Turbulence is resisting doing this… I’ve spent HOURS trying to get the emission to expand out in such a way that it naturally fills ALL of the tunnels, but I just cannot make it work.
I’d just love to know how I could make the emissions fill ALL of the internal tunnels.
My current scene (what the above animation was based on) can be downloaded here, if anybody wants to see my settings.

I am by no means an expert in Turbulence, so maybe there’s something obvious I’m missing!
ANY help in this regard would be fantastic!

A quick and dirty solution would be to create a spline that runs down the centre of the model and use that as an emitter as it grows or us a sweep on it as an emitter that grows. Messing around with your file without trying that I am simply using density and it is getting there is just takes time to fill those final bronchi. So a spline would be easier if i can remember how to make a spline from an object.

and it would help if the whole geo was in the container !!

Another option would be to fill the bronchi with fuel and have an igniter at the top with fuel set to ignite on temperature, that should fill the lungs with smoke correctly as the fuel burns along but I cannot get that geometry to fill properly, there is something odd about it. It may be a TFD issue but i suspect a geometry thing as optimise the points helps somewhat. Once filled with density you can use the exhale method you used before with a negative pressure on the igniter sphere.
EDIT : OK I am having some progress filing it but I have also found out what the issue is with the mesh, if you open it in a separate file you see it is in fact a hollowed out block and the result we see in your file is like a casting taken from that. hence when you try to use it to fill with fuel you get a block of fuel
Edit !! OK here is far as I got, just one or two endings not filing , i think perhaps a geometry issue ? I used density forced down with a separate emitter just set for normal force. No temp, no fuel, nothing but density.