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

Cfl_adapt

Register Blogs Community New Posts Updated Threads Search

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
Old   October 6, 2021, 15:58
Default Cfl_adapt
  #1
New Member
 
Join Date: Jan 2011
Posts: 22
Rep Power: 15
Speng is on a distinguished road
In the TestCases\turbomachinery\transonic_stator_2D case I'm trying to run with CFL_ADAPT turned on. I've changed the cfg to what's shown below (files is also attached) but when I run it AFAICT the CFL isn't adjusted at all. Am I missing something.

Also apparently periodic BC and multigrid aren't compatible currently what are useful ways of improving convergence? For this particular case I tried ramping the exit static pressure which had a noticeable positive impact.

% Courant-Friedrichs-Lewy condition of the finest grid
CFL_NUMBER= 40.0
%
% Adaptive CFL number (NO, YES) Default is NO this example changed to YES with appropriate CFL_ADAPT_PARAM
CFL_ADAPT= YES
%
% Parameters of the adaptive CFL number (factor down, factor up, CFL min value, CFL max value )
CFL_ADAPT_PARAM= ( 0.5, 1.2, 20.0, 100.0)
Attached Files
File Type: txt transonic_stator.txt (11.5 KB, 6 views)
Speng is offline   Reply With Quote

Old   October 7, 2021, 04:34
Default
  #2
Senior Member
 
Arijit Saha
Join Date: Feb 2019
Location: Singapore
Posts: 132
Rep Power: 7
ari003 is on a distinguished road
Quote:
Originally Posted by Speng View Post
In the TestCases\turbomachinery\transonic_stator_2D case I'm trying to run with CFL_ADAPT turned on. I've changed the cfg to what's shown below (files is also attached) but when I run it AFAICT the CFL isn't adjusted at all. Am I missing something.

Also apparently periodic BC and multigrid aren't compatible currently what are useful ways of improving convergence? For this particular case I tried ramping the exit static pressure which had a noticeable positive impact.

% Courant-Friedrichs-Lewy condition of the finest grid
CFL_NUMBER= 40.0
%
% Adaptive CFL number (NO, YES) Default is NO this example changed to YES with appropriate CFL_ADAPT_PARAM
CFL_ADAPT= YES
%
% Parameters of the adaptive CFL number (factor down, factor up, CFL min value, CFL max value )
CFL_ADAPT_PARAM= ( 0.5, 1.2, 20.0, 100.0)
Just a quick question, if you specify the freestream pressure and temperature then automatically from ideal gas law freestream density is computed. Dont you think specifying the freestream density is simply redundant? Also the density through ideal gas law is around 7.
ari003 is offline   Reply With Quote

Old   October 7, 2021, 12:24
Default
  #3
New Member
 
Join Date: Jan 2011
Posts: 22
Rep Power: 15
Speng is on a distinguished road
The config file is from the SU2 developers; the only thing I've changed is the adaptive CFL settings. This is a turbomachinery analysis of a high pressure turbine nozzle so the boundary conditions are set separately so I doubt the freestream conditions are relevant/important.
Speng is offline   Reply With Quote

Old   October 7, 2021, 14:27
Default
  #4
Senior Member
 
Pay D.
Join Date: Aug 2011
Posts: 166
Blog Entries: 1
Rep Power: 14
pdp.aero is on a distinguished road
This might help:

REF_DIMENSIONALIZATION= FREESTREAM_PRESS_EQ_ONE
__________________
since every contribution counts, always good ones are appreciated!
pdp.aero is offline   Reply With Quote

Old   October 7, 2021, 17:33
Default
  #5
New Member
 
Join Date: Jan 2011
Posts: 22
Rep Power: 15
Speng is on a distinguished road
Quote:
Originally Posted by pdp.aero View Post
This might help:

REF_DIMENSIONALIZATION= FREESTREAM_PRESS_EQ_ONE
That didn't make the CFL vary.
Speng is offline   Reply With Quote

Reply


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



All times are GMT -4. The time now is 18:58.