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Gas in a venturi pipe
Posted 28.09.2009, 08:19 GMT-4 2 Replies
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Hi there, I have recently tried to simulate a 2D gas flow in a venturi pipe. Unfortunately it always returns a convergence error. I am not sure if it is due to the boundary conditions I set for the pipe.
I attached the file of the venturi model and I wonder if someone could kindly take a look and perhaps give me some advice on how to make the model work.
Thanks in advance!
I attached the file of the venturi model and I wonder if someone could kindly take a look and perhaps give me some advice on how to make the model work.
Thanks in advance!
Attachments:
2 Replies Last Post 28.09.2009, 16:35 GMT-4
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Posted:
1 decade ago
There are several issues I noticed with your model.
1- Your Reynolds number is ~ 55,000 meaning your flow is turbulent, but you are using a laminar flow model. This may not converge at all, or if it does the solution will be wrong. You need to use a turbulence model (if you have Chemical Engineering module). I suggest you use k-omega model in favor of k-epsilon if you can get it to work at all (I never could, but it is supposed to be the more physically realistic of the two models for confined flows)
2- your mesh at the entry leg seems too coarse.
3- This being a circular venturi pipe you need to use a 2D axisymmetric model, not just 2D.
4- with axial symmetry, be careful to model only one half of the pipe with the centerline lying on the symmetry axis.
These are just to set up the physical problem correctly. After doing all these you may still have convergence problems because turbulence is not easy to model. In that case you want to play with solver settings, and various turbulence modeling tuning parameters etc.
Good luck
Ozgur
1- Your Reynolds number is ~ 55,000 meaning your flow is turbulent, but you are using a laminar flow model. This may not converge at all, or if it does the solution will be wrong. You need to use a turbulence model (if you have Chemical Engineering module). I suggest you use k-omega model in favor of k-epsilon if you can get it to work at all (I never could, but it is supposed to be the more physically realistic of the two models for confined flows)
2- your mesh at the entry leg seems too coarse.
3- This being a circular venturi pipe you need to use a 2D axisymmetric model, not just 2D.
4- with axial symmetry, be careful to model only one half of the pipe with the centerline lying on the symmetry axis.
These are just to set up the physical problem correctly. After doing all these you may still have convergence problems because turbulence is not easy to model. In that case you want to play with solver settings, and various turbulence modeling tuning parameters etc.
Good luck
Ozgur
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Posted:
1 decade ago
Thanks Ozgur for your kind advice :)
I will make the amendments in my model and give it a run.
I will make the amendments in my model and give it a run.