Sideslip simulation problem on version v6.61
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#213 Sideslip simulation problem on version v6.61
Hello everyone, as far as I can see nobody had reported this before (if I am wrong I apologize). I am trying to run some sideslip simulation but I am getting weird results with all the polars type that allow this kind of simulation.
I've done the same simulation with older versions and it seams like it worked until version v4.48.
I attach here both the images of the Cp as well as the test-case that I've made. As you can see the wing at alpha 0 it is fine but with beta=5 is looking very wrong.
I hope someone can tell me if there is a bug and that we can fix it.
Regards,
Luca
The likely explanation is that there is an area of locally high pressure at the wing tip. Try to change the scale of the color map.
André
Well if you look at the pressure level is way to high plus the value for CL Cm are definitely wrong (have a look at the picture in attachment). You can see in the other picture in attachment that the Cp in general looks wrong which also should be the cause of Cl Cm Cd values being so off.
Also if I compare the results with the older versions (v4.47) I can see that there is a problem. Can you check that?
Luca
Last edit: luca moretti 2024-06-08
Bug confirmed.
fixed with commit 1493
Many thanks Adrè. How can I download this fixed version? is it already included in the v6.61?
EDIT: I've managed to check this new version and compare it to the previous one (v6.61). The first thing I am noticing is that the Cl vs alpha curve for beta=0 is very strange. It looks like the Cl slope is almost half of what it sould be. Also the Cl_0 looks wrong because is negative for a normally cambered NACA foil.
Can you check it Andrè?
Thanks in advance.
Regards,
Luca
Last edit: luca moretti 2024-06-16
I had missed something which should be fixed with the latest commit.
André
Many thanks Andrè. I've tested the latest commit (1496) and now looks like it works with sideslip simulation. One question though: if I compare the results with the version v6.47 I can see that the beta=0 curve is now identical but as beta increases the differences between the two version also increase.
In attachment you can see a comparison between v6.47 and v6.62 for cl vs alpha at 3 different values of betas (0 20 40 deg), you can see that slope in the newer version is higher than in the old one especially in the alpha>0 region.
Is there a specific reason for that?
Luca