Is there any way in freefem, we can implement rotation boundary condition

Dear FreeFem++ team, I know in the PDE, we can do on(Label,ux=0,uy=0) to apply the boundary condition to close the displacement . However, I was wondering how can we constrain a disc displacement (ux, uy) at its center without closing the Rz rotation. [we do not want it to move up and down but can freely rotate].

Thank you so much for your time

Probably not the answer about how to do it in Freefem, but I would do a coordinate transformation to pass to the co-rotating frame…

Hello Julien, thank you for the answering, would you mind give me some simple examples about this idea? Thank you.

Can you send a real model of your problem, because can have lot of way to modélise a rotating objet.

yes frederic, thank you for your reply. you can see the image I send here. we want to make the right hole can freely rotate in Y axis. I also attached one of my mesh file here. [label 12 is the load hole, label 6 is the clamped hole, and label 5 is the rotate hole]
REAL_CASE.mesh (232.5 KB)
Thank you

OK, I static case you can do penalization on rotation boundary normal displacement is zero: like in this example
elas-rot.edp (1.4 KB)

remark, you can play with boundary condition to see the difference .

Thank you so much Frederic, I think this is exactly what I want.