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"Failed to find a solution. Divergence of the linear iterations. Returned solution is not converged."
Posted 16 juil. 2012, 06:19 UTC−4 4 Replies
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I have been receiving this error message - "Failed to find a solution. Divergence of the linear iterations. Returned solution is not converged."
fyi, I run a stationary state, following by a transient state, at once. There is no injection/production temperature/pressure in the stationary state, but only hydraulic head, initial temperature, heat source. As for the transient state, initial temperature is taken away and replaced by the solution from stationary state; a new injection temperature/pressure is added.
I have been working around with mesh, and different BCs, but nothing works.
Any ideas?
Thanks!
Liwah
fyi, I run a stationary state, following by a transient state, at once. There is no injection/production temperature/pressure in the stationary state, but only hydraulic head, initial temperature, heat source. As for the transient state, initial temperature is taken away and replaced by the solution from stationary state; a new injection temperature/pressure is added.
I have been working around with mesh, and different BCs, but nothing works.
Any ideas?
Thanks!
Liwah
4 Replies Last Post 20 juil. 2012, 03:24 UTC−4
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Posted:
1 decade ago
Hi
check carefull if you have the results of the stationay study that are couple as initial solution for the time series study (dependent variable solver sub-node). If this is OK, then you must have a BC missing or something that makes your time series solution unique, or perhaps the time stepping settings (if you have a periodic BC condition, use a time stepping of strict or intermediat and NOT automatic type
--
Good luck
Ivar
check carefull if you have the results of the stationay study that are couple as initial solution for the time series study (dependent variable solver sub-node). If this is OK, then you must have a BC missing or something that makes your time series solution unique, or perhaps the time stepping settings (if you have a periodic BC condition, use a time stepping of strict or intermediat and NOT automatic type
--
Good luck
Ivar
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Posted:
1 decade ago
hey
i am trying to simulate a laminar 3d pipeflow.
my pipe is oriented in vertical direction and fluid is flowing from up to down with an inlet normal velocity of 10^-5.
i have used gravity as volume force and applied in downward vertical direction and the outlet pressure i have specified is 0( i dont know whether it should be zero or something else.).
i have used LU preconditioner but it's showing the same error i.e., "Divergence of the linear iterations.
Returned solution is not converged."
please help me out.
regards
i am trying to simulate a laminar 3d pipeflow.
my pipe is oriented in vertical direction and fluid is flowing from up to down with an inlet normal velocity of 10^-5.
i have used gravity as volume force and applied in downward vertical direction and the outlet pressure i have specified is 0( i dont know whether it should be zero or something else.).
i have used LU preconditioner but it's showing the same error i.e., "Divergence of the linear iterations.
Returned solution is not converged."
please help me out.
regards
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Posted:
1 decade ago
Hi,
I believe you should have an inlet boundary condition and a corresponding "Outlet-Zero pressure, no viscous stress" boundary condition. All other boundary condition should be no-slip. Most of the times, I get this error when it's a meshing issue, so try making the mesh really really fine. Also, try BICGSTAB solver.
Hope this helps!
-Nitesh
I believe you should have an inlet boundary condition and a corresponding "Outlet-Zero pressure, no viscous stress" boundary condition. All other boundary condition should be no-slip. Most of the times, I get this error when it's a meshing issue, so try making the mesh really really fine. Also, try BICGSTAB solver.
Hope this helps!
-Nitesh
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Posted:
1 decade ago
Hi,
To put it simply, Comsol has stopped working with incomplete LU iterative solver (don't ask me why) in CFD, you may switch to a direct method if you have enough RAM or to a multigrid iterative solver.
It would be interesting to know whether incomplete LU stopped working also for other packages, does anyone know?
Cheers
To put it simply, Comsol has stopped working with incomplete LU iterative solver (don't ask me why) in CFD, you may switch to a direct method if you have enough RAM or to a multigrid iterative solver.
It would be interesting to know whether incomplete LU stopped working also for other packages, does anyone know?
Cheers