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Note: This discussion is about an older version of the COMSOL Multiphysics® software. The information provided may be out of date.

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

Posted 2011年5月1日 GMT-4 15:41 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 2011年7月13日 GMT-4 09:38
mattachu
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Posted: 1 decade ago 2011年5月3日 GMT-4 08:59
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 2011年5月3日 GMT-4 16:40
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 2011年5月3日 GMT-4 22:00
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 2011年5月4日 GMT-4 02:06
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 2011年7月13日 GMT-4 09:38
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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