[Question] Behavior of DV_VALUE with Hicks and Henne bump functions

[r-ashwin]

If I set DV_KIND = HICKS_HENNE, then what exactly does DV_VALUE do? I see that it deforms the mesh, but I am trying to understand how exactly DV_VALUE (a scalar) is related to the vector of design variables defined in DEFINITION_DV?

Thanks for your help and apologies if this is documented elsewhere--I searched for it a bit but could not find a definition.

Edit1:
Just to add some context, I want to write a Python function that implements f, df = function(x), where x is the vector of design variables (e.g., Hicks and Henne bump function coefficients). I tried to modify the shape_optimization.py to implement this, where I essentially ignore the calls to the optimizer (and I use project.obj_f(x) and project.obj_df(x) for this). However, the time it takes to evaluate the objective function and gradient this way, suggest that it might not be utilizing parallel computing (note that the code is successfully compiled and tested for parallel scale up). On the other hand, running discrete_adjoint.py for the same config file, computes the forward and adjoint solutions at a fraction of the time. For example, with 36 cores, the first approach takes ~15minutes whereas the second approach takes ~1minute.

Therefore when I run discrete_adjoint.py, the script reads the mesh file to infer the geometry deformations and runs the forward and adjoint solvers on it. It appears that the way to generate a deformed mesh is to adjust DV_VALUE in the config file, run SU2_DEF and then used the deformed mesh. However, I am not sure how the scalar-valued DV_VALUE is related to the design vector x?

Edit2:
It appears that DV_VALUE essentially does the deformation at DV_PARAM.

How can I pass an array of DV_VALUE at list of DV_PARAM tuples? When I just tried passing a comma-separated list, I see that it ignores all inputs but the first one.

[r-ashwin]

@pcarruscag Would appreciate some feedback when you get a chance. Thank you!

[pcarruscag]

I never used them, hopefully some other SU2 volunteer will chime in on this one.
Cheers
PS Attach the config.

[r-ashwin]

Okay thanks feel free to tag the most appropriate volunteer.

I have attached the config file. I set DV_PARAM = (1, 0.25), (0, 0.25) and DV_VALUE = 0.001, 0.001. It ignores the second () in DV_PARAM.

turb_SA_RAE2822.cfg.txt

[pcarruscag]

For FFD you need as many DV_KIND as DV_PARAM and DV_VALUE, might be the same for HH

[r-ashwin]

Turns out that is true. Thanks!