CFD Online Logo CFD Online URL
www.cfd-online.com
[Sponsors]
Home > Forums > Software User Forums > SU2

Slow convergence for NACA 0012

Register Blogs Members List Search Today's Posts Mark Forums Read

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
Old   May 6, 2024, 06:39
Default Slow convergence for NACA 0012
  #1
New Member
 
Tomas Perez Zapico
Join Date: Mar 2023
Posts: 17
Rep Power: 3
tomaspzapico is on a distinguished road
Hello,

I am trying to run a turbulent NACA 0012 simulation with SA and JST. I am using a CFL of 5 but it took a large and not reasonable number of iterations for it to converge. I tried to accelerate the convergence by using the CFL_ADAPT parameter, but when I monitor it I see that, even though it is supposed to follow the equation mentioned in this post CFL Adapt parameter, it just multiplies the old CFL by the factor I put in the configuration file each iteration until it reaches the maximum CFL (50, because with higher values the solution diverges). Nevertheless, this did not help much as it only reduced the number of iterations from 22000 to 20000 more or less.

I have also tried running the simulation for a number of iterations and then restarting it, but nothing seems to work. Additionally, I have reduced the convergence criterion from 0.01 d.c. to 1 d.c., but it provided a solution with a very high error when compared to other solvers and experimental data.

Could anyone help me please? You will find the mesh and configuration files in the following link: https://github.com/tomaspzapico/SU2.git
tomaspzapico is offline   Reply With Quote

Old   May 6, 2024, 15:00
Default
  #2
Senior Member
 
bigfoot
Join Date: Dec 2011
Location: Netherlands
Posts: 672
Rep Power: 21
bigfootedrockmidget is on a distinguished road
Hi,
You have to make the repository public :-)


We have many naca0012 tests in the testcases section of the su2 repository. Most of them work pretty well and converge within 1000 iterations. On pure triangular meshes or pure quadrilateral meshes, multigrid also works pretty well. Maybe you can check what the difference is in setup between what is in the repository and what you have?

If in the end it is the mesh, then it would be good to check what makes your mesh different from other meshes.
bigfootedrockmidget is offline   Reply With Quote

Old   May 6, 2024, 17:08
Default
  #3
New Member
 
Tomas Perez Zapico
Join Date: Mar 2023
Posts: 17
Rep Power: 3
tomaspzapico is on a distinguished road
I have already made it public.
tomaspzapico is offline   Reply With Quote

Old   May 8, 2024, 02:54
Default
  #4
Senior Member
 
bigfoot
Join Date: Dec 2011
Location: Netherlands
Posts: 672
Rep Power: 21
bigfootedrockmidget is on a distinguished road
Just switch off the MUSCL scheme for the turbulence equations. And this case also benefits from multigrid, if you lower the relaxation factors a bit.
bigfootedrockmidget is offline   Reply With Quote

Old   May 12, 2024, 07:14
Default
  #5
New Member
 
Tomas Perez Zapico
Join Date: Mar 2023
Posts: 17
Rep Power: 3
tomaspzapico is on a distinguished road
Thanks for your response. I had also tried switching off the MUSCL reconstruction for the turbulence equations, but the results for the CL and CD were further away from the experimental data I am using. I will give the multigrid a look in order to accelerate the convergence.
tomaspzapico is offline   Reply With Quote

Old   May 12, 2024, 10:36
Default
  #6
Senior Member
 
bigfoot
Join Date: Dec 2011
Location: Netherlands
Posts: 672
Rep Power: 21
bigfootedrockmidget is on a distinguished road
muscl for turbulence equations is not very robust at the moment. If the results are still far away, you might need a finer mesh.
bigfootedrockmidget is offline   Reply With Quote

Old   May 13, 2024, 02:58
Default
  #7
New Member
 
Tomas Perez Zapico
Join Date: Mar 2023
Posts: 17
Rep Power: 3
tomaspzapico is on a distinguished road
I mean that with MUSCL on for the turbulence equations I got more accurate results than without MUSCL
tomaspzapico is offline   Reply With Quote

Reply

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
Slow convergence CHTSimpleFoam OF5x mwaqas OpenFOAM Running, Solving & CFD 0 August 22, 2019 05:25
Very slow convergence AlbertoPi SU2 1 June 4, 2017 21:06
Convergence becomes very slow after adding thin material model for CHT Anna Tian CFX 1 June 6, 2013 19:03
Slow convergence using mass flow BC vitulaaak CFX 4 November 7, 2012 11:22
Force can not converge colopolo CFX 13 October 4, 2011 23:03


All times are GMT -4. The time now is 02:15.