Problem with FFD-based shape optimization: all gradients are zero
Hello
I was doing a shape optimization with v1.1 which I am now trying with v2.0 With v2.0 I find that in the very first iteration, all gradients turn out to be zero. I attach below some output from the two versions of SU2_GPC With v1.1: Code:
---------- Start gradient evaluation using surface sensitivity ---------- Code:
---------- Start gradient evaluation using surface sensitivity ---------- Code:
NCHUNK= 1 |
5 Attachment(s)
Hi Praveen,
The optimization stuff in release 2.0 is much better than 1.1. In particular in 2.0 the entire optimization loop is in parallel (including deformation, gradient computation, etc.) The specification of ffd box looks like fine. Just to be sure, could you please repeat the problem that we described in our last workshop. You can find the .pdf of the presentation here: http://su2.stanford.edu/news/news_20130115.html I also attach the config file and some pictures with the results. Attachment 18292 Attachment 18297 Attachment 18291 Attachment 18296 Attachment 18294 Thanks a lot for your feedback, Best, Francisco |
Hello Francisco
I ran the inviscid oneram6 optimization included in su2 and used your config file (changed EXT_ITER to 1000). The optimization stops after first iteration since all the gradients are zero. The entire directory is here (about 130 MB) http://math.tifrbng.res.in/~praveen/...oneram6_v2.tgz There is a "log" file inside that which contains the screen output. |
Quote:
$ SU2_MDC inv_ONERAM6.cfg $ mv mesh_out.su2 mesh_ONERAM6_inv_FFD.su2 change the name of the mesh input file in inv_ONERAM6.cfg instead of MESH_FILENAME= mesh_ONERAM6_inv.su2 use MESH_FILENAME= mesh_ONERAM6_inv_FFD.su2 and run the continuous adjoint gradient computation and check that the gradients are not zero. $ continuous_adjoint.py -f inv_ONERAM6.cfg -p 6 In short, if you are gonna do design, the .su2 mesh should contain all the FFD information (including parametric coordinates) from the very beginning. I also recommend to run the optimization scripts with RESTART_SOL= YES, so you need a flow and adjoint flow solution before starting the optimization process. Best, Francisco |
After following your instructions exactly, I am able to run the oneram6 problem.
But I am facing a problem for my own shape optimization case. I ran upto Step 5 but during Step 6 I get this error Code:
------------------- Config file boundary information -------------------- |
1 Attachment(s)
The shape sensitivity does not look correct. I can see the domain partitions in the attached plot. Is this normal behaviour with parallel computation visualization ?
|
Yep, this is a visualization artifact that we are gonna solve as soon as possible.
Cheers, Francisco |
Quote:
|
Quote:
http://su2.stanford.edu/news/news_20130922.html you will find a presentation and the config files for the optimal design of ONERA M6 using the current version of SU2 in the https://github.com/su2code repository (our recommendation is to fork the repository if you are gonna introduce any change in the code). Best, Francisco |
Francisco,
Tom pointed out the issue I was having earlier this morning regarding how specification of FFD boxes has been re-defined in more recent versions of the code, but I appreciate you pointing to where the workshop materials have been posted on your site. Would you be willing to explain in a bit more detail how the MAX_THICKNESS_SEC? values being used as geometric constraints in addition to the lift coefficient were arrived at in the configuration file posted with this case? They don't seem to correspond to the max thickness values of the airfoil sections resulting from the geometry design code, so I was curious how one goes about setting these. Thanks! |
Quote:
He have posted all the workshop documentation in http://su2.stanford.edu/training.html The use of MAX_THICKNESS_SEC is described in the workshop documentation Best, Francisco |
All times are GMT -4. The time now is 20:04. |