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Failed to find the consistent initial values

Posted 2013年2月12日 GMT-5 00:20 Fluid & Heat, Heat Transfer & Phase Change, Computational Fluid Dynamics (CFD), Geometry, Materials, Mesh, Modeling Tools & Definitions, Parameters, Variables, & Functions, Results & Visualization, Studies & Solvers Version 5.1 3 Replies

Nithin
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Dear sir,

I am getting an error after solving as follows

"Failed to find the consistent initial values
Last time step is not converged.
- Feature : Time - Dependent Solver1 (sol1/t1)
- Error : Failed to find consistent initial values"

We suppose that the error is because of the fact that I am unable take back the results from 1440th time step to 0th time step (with an interval of 5 min each). Is that correct and how can I use the results of the 1440th minute back in oth minute for accurate values??

If not, what are the probable corrections for this error??

And, we have a prolonged query about the varying temperature of the fluid as it flows through the pipes. As the fluid flows through the pipe, the initial values of fluid temperature my vary from position to position. So, Can you let me know about how to incorporate this condition in the model of ours??

Thanking You sir.

Nithin
3 Replies Last Post 2015年9月18日 GMT-4 06:42
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)
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Posted: 1 decade ago 2013年2月12日 GMT-5 11:05
Hi

if you do time transient solving in "automatic time steps" the COMSOL sover is set up for diffusion type solvers, so it expects to be able to take larger and larger steps, ut if you introduce periodic BC conditions, the solver might step over a transition.

Try the solver settings time stepping (far down in the solver tree) and use intermefdiate or strickt (check the doc) and be sure a few steps are on the transitions. Then use "smooth transitions, "step" funcions, and NOT Dirac steps

--
Good luck
Ivar
Hi if you do time transient solving in "automatic time steps" the COMSOL sover is set up for diffusion type solvers, so it expects to be able to take larger and larger steps, ut if you introduce periodic BC conditions, the solver might step over a transition. Try the solver settings time stepping (far down in the solver tree) and use intermefdiate or strickt (check the doc) and be sure a few steps are on the transitions. Then use "smooth transitions, "step" funcions, and NOT Dirac steps -- Good luck Ivar
Nithin
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Posted: 1 decade ago 2013年2月14日 GMT-5 23:55

Hi

if you do time transient solving in "automatic time steps" the COMSOL sover is set up for diffusion type solvers, so it expects to be able to take larger and larger steps, ut if you introduce periodic BC conditions, the solver might step over a transition.

Try the solver settings time stepping (far down in the solver tree) and use intermefdiate or strickt (check the doc) and be sure a few steps are on the transitions. Then use "smooth transitions, "step" funcions, and NOT Dirac steps

--
Good luck
Ivar


Sir..

I have made the corrections suggested by you in the above comment. But still, the problem persists. I request you to have a look of the model in the link and help me out.

www.sendspace.com/file/d1vtq3

Thanking You sir...

Nithin
[QUOTE] Hi if you do time transient solving in "automatic time steps" the COMSOL sover is set up for diffusion type solvers, so it expects to be able to take larger and larger steps, ut if you introduce periodic BC conditions, the solver might step over a transition. Try the solver settings time stepping (far down in the solver tree) and use intermefdiate or strickt (check the doc) and be sure a few steps are on the transitions. Then use "smooth transitions, "step" funcions, and NOT Dirac steps -- Good luck Ivar [/QUOTE] Sir.. I have made the corrections suggested by you in the above comment. But still, the problem persists. I request you to have a look of the model in the link and help me out. http://www.sendspace.com/file/d1vtq3 Thanking You sir... Nithin
Bilal Javed Butt
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Posted: 9 years ago 2015年9月18日 GMT-4 06:42
Hi Nithin,

I am also getting same error. could you please help me out in this? How did you resolve your issue, Waiting for your help.


Thanks,
Bilal
Hi Nithin, I am also getting same error. could you please help me out in this? How did you resolve your issue, Waiting for your help. Thanks, Bilal

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