Airstream Modeling with Comsol: Problems & Solutions

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1234frank1234
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I'm making a model in Comsol.
In it air streams from a pressure chamber through a small jet (1 mm).
It seems i am having problems with it because i can't get the tolerance or getting different errors.
I have revined the mesh as much as the computer can handle but i stil don't make it.
Is this a comon problem with simulating a airstream or do i need some different solver or so?
 
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What errors are you getting? Also what modules are you using? Incompressible, weakly compressible, or compressible? I've never modeled air streams before but the physics of it are relatively simple and you should at least get some type of answer.
 
Sorry for the late reply.
I have tried both incompressible and weakly compressible.
After the error occurred i do get a result but i think it is questionable how much i can rely on that.
The errors i get are:

Failed to find a solution:
No convergence, even when using the minimum damping factor.
Returned solution has not converged.

Also it happens that i can run it for ages with iterations above 1000 and i still didn't get a result.
 
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It sounds like a solution can not be found for your model. Are you using only the navier-stokes module? If not, try solving the modules one at a time using the solver manager. If your only use the one, then you need to simply/modify your model so a solution can be found. Comsol is pretty good about converging and usually does so rather quickly. If it can't find a solution there s a good chance something is wrong with your model.
 
does this use a moving mesh?
 
Were you able to model your problem? I am also working on a similar project and can't model the air jet when it comes out of the nozzle at low pressure.


1234frank1234 said:
I'm making a model in Comsol.
In it air streams from a pressure chamber through a small jet (1 mm).
It seems i am having problems with it because i can't get the tolerance or getting different errors.
I have revined the mesh as much as the computer can handle but i stil don't make it.
Is this a comon problem with simulating a airstream or do i need some different solver or so?