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Fluid flow through a pipe; Failed to find a solution.

Posted 1 mag 2011, 15:41 GMT-4 Fluid & Heat, Studies & Solvers Version 4.1 5 Replies

Juan Lopez Arriaza
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I am relatively new to comsol and I am attempting to model water flow through a pipe given pressure head at inlet and outlets. My geometry is simple, it is a cylinder with radius 1mm and length 2mm. I am using the laminar flow model. The pressure head value at both inlet and outlet are not important to my calculations and i have a no slip boundary condition on the edges.

Whenever i attempt to run the model i receive the error: Failed to find a solution.

Anybody have any suggestions as to what i might try?

Thank You
5 Replies Last Post 13 lug 2011, 09:38 GMT-4
mattachu
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Posted: 1 decade ago 3 mag 2011, 08:59 GMT-4
I'd also like to hear any suggestions as I'm modelling something similar. I can get it to work with a velocity profile inlet and fixed pressure outlet, but when I try to change the boundary conditions, the solver fails to find a solution.
I'd also like to hear any suggestions as I'm modelling something similar. I can get it to work with a velocity profile inlet and fixed pressure outlet, but when I try to change the boundary conditions, the solver fails to find a solution.
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)
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Posted: 1 decade ago 3 mag 2011, 16:40 GMT-4
Hi

if you are in turbulent mode, it could come from a to coarse mesh, I just had one of those surprises ;)

--
Good luck
Ivar
Hi if you are in turbulent mode, it could come from a to coarse mesh, I just had one of those surprises ;) -- Good luck Ivar
Juan Lopez Arriaza
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Posted: 1 decade ago 3 mag 2011, 22:00 GMT-4
Ivar,
I've actually thought about the problem of entering a turbulent flow regime so I've attempted to run the simulation with Boundary Conditions that provide a small head difference between outlet and inlet.

I have also run the simulation with a finer mesh and it still does not find a solution.

Any other suggestions?

Thanks
Juan
Ivar, I've actually thought about the problem of entering a turbulent flow regime so I've attempted to run the simulation with Boundary Conditions that provide a small head difference between outlet and inlet. I have also run the simulation with a finer mesh and it still does not find a solution. Any other suggestions? Thanks Juan
Amir Fadel
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Posted: 1 decade ago 4 mag 2011, 02:06 GMT-4
Hi,

It may be due to the fact you have pressure condition both at the inlet and at the outlet but without looking at the model itself I can't guarantee this is the answer.

What is the Reynolds number of your model?

Cheers
Hi, It may be due to the fact you have pressure condition both at the inlet and at the outlet but without looking at the model itself I can't guarantee this is the answer. What is the Reynolds number of your model? Cheers
Peng Xie
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Posted: 1 decade ago 13 lug 2011, 09:38 GMT-4
I have been in the same problem. I think chances are the problem is that the Reynold's number becomes too high. you can try to lower the velocity
I have been in the same problem. I think chances are the problem is that the Reynold's number becomes too high. you can try to lower the velocity

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