Using abaqus to model lifting gas

[AdamBown]

Morning All,

Any one here ever used the fluid cavities of abaqus to model a bag of some description filled with a lifting gas, e.g. hydrogen, helium or hot air?
It is getting the varying pressure distribution I am interested in. I know this can be done using user subroutine vdload, but I am wondering if it could be done with just the parameters of the fluid cavities, e.g. density
Cheers.
Adam.

 

[burningDiesel]

There is an airbag inflation example in the manual, maybe this is what you want and if not, you can elaborate on why not

 

[AdamBown]

Sdebock,

Thank you for taking the time to reply. I have been able to use fluid cavities before to model gas filled, surface defined bags as in that air bag example.

The difference with my new particular example is that I want to try and replicate the buoyant behaviour of a lifting gas such as hot air or helium. One of the entries for fluid cavities is density, so I was wondering if I had a helium filled (fluid cavity) bag within an air filled (fluid cavity) environment, the respective densities of the two gases will mean the inner helium bag will take up the classic hot air balloon shape, within the heavier density gas.

However, the more I look into this, the more I don't think this is the case. It seems that the inputs for fluid cavities are purely to facilitate the gas law equation calculations.
Hope this makes sense?

 

[burningDiesel]

I think I understand but I dont know the answer
Maybe modeling with eulerian elements (CEL) + a gravity load would be a better approach maybe.