Continuity issues

Rookier · July 2, 2018, 15:02

Hi everyone,
I am simulating flow past the airfoil NACA 0012 in ANSYS Fluent.I used SA model and the required conditions.The AMS was diverging.Then I changed to K-e model,and changed the second order variables to first order.It effected my continuity residuals.They are not converging,increasing instead.
Please suggest a solution to this problem.
Thanks in advance

LuckyTran · July 2, 2018, 18:49

Reset your residuals after you switched to the new solver.

I really suggest to read thoroughly through the documentation to understand what exactly are the residuals. The continuity residual is scaled by the worst imbalance in the first 5 iterations. When you switch solvers after iteration 100, that reference value is no longer relevant. It also means your continuity residual is dependent on the initialization.

Rookier · July 2, 2018, 23:34

Hi,
I forgot to mention that I did my meshing in Hypermesh and the mesh consists of trias(Unstructured mesh).But I have checked the quality and no element is failing in skew or the aspect ratio.Will that effect my solution in anyway?
Thanks in advance.

July 2, 2018, 15:02	Continuity issues	#1
Rookier New Member Ramesh Join Date: Jun 2018 Posts: 8 Rep Power: 7	Hi everyone, I am simulating flow past the airfoil NACA 0012 in ANSYS Fluent.I used SA model and the required conditions.The AMS was diverging.Then I changed to K-e model,and changed the second order variables to first order.It effected my continuity residuals.They are not converging,increasing instead. Please suggest a solution to this problem. Thanks in advance

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July 2, 2018, 18:49		#2
LuckyTran Senior Member Lucky Join Date: Apr 2011 Location: Orlando, FL USA Posts: 5,675 Rep Power: 66	Reset your residuals after you switched to the new solver. I really suggest to read thoroughly through the documentation to understand what exactly are the residuals. The continuity residual is scaled by the worst imbalance in the first 5 iterations. When you switch solvers after iteration 100, that reference value is no longer relevant. It also means your continuity residual is dependent on the initialization.

July 2, 2018, 23:34		#3
Rookier New Member Ramesh Join Date: Jun 2018 Posts: 8 Rep Power: 7	Hi, I forgot to mention that I did my meshing in Hypermesh and the mesh consists of trias(Unstructured mesh).But I have checked the quality and no element is failing in skew or the aspect ratio.Will that effect my solution in anyway? Thanks in advance.