Tdr Residual does not converge
 

Hello,

My problem, as you can see in the attached plot is that the tdr residual does not converge whereas all the others do.

The simulation is flow in a duct with inlet velocity and outlet pressure boundary conditions. In the middle of the duct there is a metal sheet with holes so that the fluid can only cross to the other side of the sheet through these holes. The fluid inlet velocity is between 1 and 10 m/s. The duct is a 10 cm square duct. The sheer has 50 holes with 2 mm diameter.

Looking at the results everything seems to make sense. There is a great pressure drop in the metal sheet. The fluid accelerates as it passes through the holes etc. However, the Tdr residual is too high.

Can you please help me?
Did anyone have a similar experience?

Thank you very much and please let me know if you need additional information.

Alvaro

Your solution is not converged at all.
Residuals only dropped one order in magnitude, which is not considered converged. I would not trust these results if I were you.
For the solution to be accurate, residuals need to drop at least 6 orders in magnitude.

What physics models have you used?
I would try playing around with the models a little bit and changing them around.
Also, increasing mesh quality always helps, as well as reducing under relaxation factors.

Solution is not converged. However, it does not look as though it is ever going to converge no matter how many time steps I run because the Tdr residual is not getting smaller. I've tried even 9.5 million cells which for a 10x10x80 cm duct with slip condition on the duct walls and 1 m/s inlet velocity is in my opinion a big number.

The models are:

Ideal Gas
K-e Turbulence (Also tried k-w and same thing happened)
Steady
Coupled Flow
And all the default ones

The mesh is tetrahedral with surface remesher and concentrating cells 4 to 1 in the middle part of the duct where the perforated sheet is located. I've tried several meshing models too and obtained the same results.

Thanks!

If tdr is having issues generally the problem is with your prism mesh. What does that look like? Can you post images of your mesh? And why are you using the tet mesher? The polymesher or trimmer will give superior results.

hi
 

i am facing the same problem , so what do you deal with the problem finally. can you help me, forgive my poor english. thanks a lot!

hello,
Try to change the model from couple into segregated. This might work. Thanks.

Yuanming