Residuals-Ccontinuity

Lifen09 · March 13, 2020, 04:46

Hello dear all,

I am a newbie using ANSYS Fluent. I have a 3D model which's inlet is velocity inlet and outlet is is pressure outlet. I tried to solve it for three different mesh models and for each I got different solutions. I enter all values same, only mesh is different. I am also employing a formula, so it is interesting that the one with more fluctuations in continuity residual gets closer to the formula output. I am attaching residuals to this thread, I would be really happy if anyone let me know which one is more correct.

Thank you beforehand. 61FAFF94-35E8-45EA-AD3E-605A841B518D.jpg

CA95B243-2070-4B51-BBC1-6D1D4046AD96.jpg

E3F17C95-AD66-431C-85FA-AC7E2636CE7F.jpg

vinerm · March 13, 2020, 05:35

Residuals alone are not good indicators of convergence. You have to monitor some other quantity, such as pressure at inlet, to measure convergence.

Convergence does not imply accuracy, only that the field is converged for a given set of conditions.

So, better would be to set a few monitors in all cases and then observe how much do they change over iterations and from case to case.

March 13, 2020, 04:46	Residuals-Ccontinuity	#1
Lifen09 New Member Elif Gündoğdu Join Date: Mar 2020 Posts: 2 Rep Power: 0	Hello dear all, I am a newbie using ANSYS Fluent. I have a 3D model which's inlet is velocity inlet and outlet is is pressure outlet. I tried to solve it for three different mesh models and for each I got different solutions. I enter all values same, only mesh is different. I am also employing a formula, so it is interesting that the one with more fluctuations in continuity residual gets closer to the formula output. I am attaching residuals to this thread, I would be really happy if anyone let me know which one is more correct. Thank you beforehand. 61FAFF94-35E8-45EA-AD3E-605A841B518D.jpg CA95B243-2070-4B51-BBC1-6D1D4046AD96.jpg E3F17C95-AD66-431C-85FA-AC7E2636CE7F.jpg

March 13, 2020, 05:35	Residuals	#2
vinerm Senior Member Vinerm Join Date: Jun 2009 Location: Nederland Posts: 2,946 Blog Entries: 1 Rep Power: 35	Residuals alone are not good indicators of convergence. You have to monitor some other quantity, such as pressure at inlet, to measure convergence. Convergence does not imply accuracy, only that the field is converged for a given set of conditions. So, better would be to set a few monitors in all cases and then observe how much do they change over iterations and from case to case. __________________ Regards, Vinerm PM to be used if and only if you do not want something to be shared publicly. PM is considered to be of the least priority.

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