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 The information provided may be out of date.

Discussion Closed This discussion was created more than 6 months ago and has been closed. To start a new discussion with a link back to this one, click here.

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

Please login with a confirmed email address before reporting spam

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 13.07.2011, 09:38 GMT-4

Please login with a confirmed email address before reporting spam

Posted: 1 decade ago 03.05.2011, 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)

Please login with a confirmed email address before reporting spam

Posted: 1 decade ago 03.05.2011, 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

Please login with a confirmed email address before reporting spam

Posted: 1 decade ago 03.05.2011, 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

Please login with a confirmed email address before reporting spam

Posted: 1 decade ago 04.05.2011, 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

Please login with a confirmed email address before reporting spam

Posted: 1 decade ago 13.07.2011, 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

Note that while COMSOL employees may participate in the discussion forum, COMSOL® software users who are on-subscription should submit their questions via the Support Center for a more comprehensive response from the Technical Support team.