[Zen]

Hello everybody,

How is the reference area used in the computation of the aerodynamics coefficients?
For example, is the drag coefficient computed integrating the pressure and viscous forces and then dividing this number by the reference area and dynamic pressure?

Thanks in advance,

Z

[hlk]

Originally Posted by Zen

Hello everybody,

How is the reference area used in the computation of the aerodynamics coefficients?
For example, is the drag coefficient computed integrating the pressure and viscous forces and then dividing this number by the reference area and dynamic pressure?

Thanks in advance,

Z

Yes.

If you set the reference area in the config file to 0 the code will compute the reference area by projection of the solid walls into the Z plane.
Length is also required for moment coefficients.

[Zen]

Thanks Heather for the answer. Then maybe you can help me figuring out the problem that I am having.

I am using SU2 V3.2.2., I know it's quite an old version but that's the one I am working with at the moment.

I set REF_AREA=0 and OPT_OBJECTIVE = DRAG*0.1 for the optimization of a wing perpendicularly attached on a flat plate. I imposed that only the flat plate can be deformed in the spanwise direction.

I want to minimize the drag but the code instead optimizes the drag coefficient by increasing the projected area in the z-plane. When I check my log file, I see the voice "Area projection in the z-plane" changing and increasing.

If I re-run the same optimization with REF_AREA=0.305 (the reference area of the baseline configuration) I would expect the voice "Area projection in the z-plane" to stay constant. However, it still changes.

Maybe this is just a piece of info that SU2 is outputting in the log file, while it actually keeps the area constant but even this new optimization seems to be optimizing the drag coefficient by increasing the projected reference area instead of optimizing the drag.

Could you please throw some light on this problem?

Thanks a lot,

Z