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Old   December 30, 2012, 12:25
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Amin
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Hi everyone
I'm simulating mass flow distribution in micro-channel manifolds.
The solution does not converge unless I change the Momentum Under Relaxation Factor. I read somewhere in this forum that we are not allowed to decrease the Momentum URF less than 0.5 But as I decrease it less than 0.5 the solution converges faster. Is it OK to reduce URF this way?
I encountered an other problem too. Although the residuals are less than 1e-04, there is obvious different in mass flow rate in different number of iterations.
could you please help me?

Regards,
Amin
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Old   December 31, 2012, 00:33
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For Microchannel, first use double precision, second decrease URF of the UDF for wall slip profile. It's easy to converge it. Try more
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Old   January 6, 2013, 16:48
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rasoul b
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Quote:
Originally Posted by msaeedsadeghi View Post
For Microchannel, first use double precision, second decrease URF of the UDF for wall slip profile. It's easy to converge it. Try more
Hi,

I want to simulate turbulent channel flow with slip B.C (by LES), But the problem doesn't converge, so can you guide me for URF for momentum & pressure? if you have any other comment, please write it.

Thanks
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Old   January 7, 2013, 01:09
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Quote:
Originally Posted by rasoulb View Post
Hi,

I want to simulate turbulent channel flow with slip B.C (by LES), But the problem doesn't converge, so can you guide me for URF for momentum & pressure? if you have any other comment, please write it.

Thanks
You shouldn't ever touch the URF if you are doing LES since it is a transient simulation. If anything, you want to increase URF and make it ORF.
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