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Divergence detected in AMG solver: temperature

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Old   September 9, 2014, 01:18
Default Divergence detected in AMG solver: temperature
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hello friends,
I am working on 3-D modelling and simulation of strand in the continuous casting process.
today i got an error "Divergence detected in AMG solver: x momentum"
then i change my modal setting, i make it to transient mode and set adative in time stepping method. now it runs but after some iterations it give another error "Divergence detected in AMG solver: temperature" how to deal with this error??????
please help me...
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Old   September 9, 2014, 15:31
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Quote:
Originally Posted by R4RAHUL View Post
hello friends,
I am working on 3-D modelling and simulation of strand in the continuous casting process.
today i got an error "Divergence detected in AMG solver: x momentum"
then i change my modal setting, i make it to transient mode and set adative in time stepping method. now it runs but after some iterations it give another error "Divergence detected in AMG solver: temperature" how to deal with this error??????
please help me...
Usually this points could help the solution for prevent from this error:
Check your BCs and ensure they are correct!
Decrease urf and courant number
Change your initialization and check its with another values!
Change the solution method

If the problem exists yet, check about temporary changing in BCs and iterate some steps and then return them! For example for high temperature flows, it's better to solve its with lower values for temperature then increasing the temp!

And for your special case maybe exist some other methods for converging but I don't know about your case!
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Old   September 9, 2014, 15:41
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Also this threat could help you :

Divergence detected in AMG Solver:TEMPERATURE
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Old   September 12, 2014, 00:58
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Originally Posted by amin.z View Post
Also this threat could help you :

Divergence detected in AMG Solver:TEMPERATURE
Thanks
but I all ready done all this which you told above but it shows the same error, the only positive thing is that it calculates some iterations then shows the same error earlier it doesn't calculate the single iterations.
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Old   September 13, 2014, 05:42
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Originally Posted by R4RAHUL View Post
Thanks
but I all ready done all this which you told above but it shows the same error, the only positive thing is that it calculates some iterations then shows the same error earlier it doesn't calculate the single iterations.
I don't know about your model but for cases with large energy transferring (for example high speed rotation, large heat transfer , etc) sometimes temporary changing in BCs will prevent from divergence!
If your case have same conditions and you're sure about your grid quality I think temporary changing in BCs will help you!

and "solution method" setting could prevent from this error! Ensure that you select good setting for "scheme" & "pressure" & etc!
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Old   September 13, 2014, 05:52
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finally this way maybe help you:
turn off any setting except turbulence, especially energy equation!
then solve the solution and after converging this mode, add other setting to your model little by little and solve the problem for all of them
because energy equ. is reason of temperature errors, this way may help you to converging!
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Old   September 16, 2014, 17:44
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my simulation run properly without any error but the i am not getting the desired result.
I am using energy,k-episilon standard enhanced wall treatment and the solidification/melting model.
my b.c are -
solidous and liquidous temp are 821
inlet temp. at velocity inlet is 851 and +ve velocity
outlet is also taken as velocity inlet with temp.- 300 and -ve velocity
I got the temp. profile but not getting any solidification there.
any idea about this????????????????
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