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Periodic flow monitoring in ANSYS fluent

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Old   November 8, 2016, 12:23
Default Periodic flow monitoring in ANSYS fluent
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Shamoon Jamshed
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Dear Fellows,

I want to use periodic flow monitoring in Fluent. where you go to residuals menu and below that there is a menu for statistics. In that you monitor per/pr-grad. Which means periodic pressure gradient. Has anyone used it? I ran the iteration and its getting increasing towards some positive or probably zero value. The curve began from -9e6 which is decreasing to zero or positive (not sure) per iteration. the curve is schematically shown in Figure attached. Where should I stop? isnt the gradient very large?
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Old   March 5, 2017, 09:37
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Any reply on that? Please comment!
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Old   March 5, 2017, 22:41
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Your solution isn't converged until that periodic pressure drop is converged.

It could be positive or negative depending on the order you selected the surfaces. You should have a feel for what this number should end up at, because it's the expected pressure drop for the mass-flow that you specified.
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Old   March 6, 2017, 04:38
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Ok, but i have taken one pitch length (I mean I am modelling a helical geometry) so I took one groove and made the model sweep along z direction up to one pitch. So I do not know the exact pressure drop that should be obtained, I only know the mass flow rate. I have two translational and two rotational periodic boundaries.
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Old   March 6, 2017, 04:45
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Please see the following link as well:

Translational Boundary Conditions along with Rotational Periodic Boundary Conditions

Regards,
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Old   March 11, 2017, 06:44
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Hi,

Please any comments on the above link and the above problem, its a bit urgent! I really need help!
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Old   March 11, 2017, 06:46
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Quote:
Originally Posted by LuckyTran View Post
Your solution isn't converged until that periodic pressure drop is converged.

It could be positive or negative depending on the order you selected the surfaces. You should have a feel for what this number should end up at, because it's the expected pressure drop for the mass-flow that you specified.
And how one can see the mass flow convergence when there is no inlet and no outlet specified, I mean that in reports--> Mass flow inlet, upon which surface one can see this?
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Old   March 11, 2017, 07:32
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You should be able to select the periodic surface and report the mass flow rate. It should be very close, but won't be exactly equal to the mass flow you specified.

Since you specified the mass flow rate, it's better to monitor the pressure drop as a convergence parameter. Checking the mas flow rate only tells you how well your boundary condition is being applied, it doesn't tell you if your solution is converged or not.
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Old   March 11, 2017, 08:23
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Please see the link as well, the problem is not limited to mfr! the interpretation of results is also problematic. I am not getting correct temperature at near the exit plane, (near one of translational periodic interface) and I applied flux on the topwall.
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