# Is there any way in freefem, we can implement rotation boundary condition **URL:** \ **Category:** General Discussion\ **Created:** [August 17, 2022, 8:40pm UTC](https://community.freefem.org/t/is-there-any-way-in-freefem-we-can-implement-rotation-boundary-condition/1947 "2022-08-17T20:40:34Z")\ **Posts on this page:** 7\ **Page:** 1
**Author:** ![zcwang6](https://yyz2.discourse-cdn.com/flex030/user_avatar/community.freefem.org/zcwang6/32/371_2.png) [@zcwang6](https://community.freefem.org/u/zcwang6)\ **Post date:** [August 17, 2022, 8:40pm UTC](https://community.freefem.org/t/is-there-any-way-in-freefem-we-can-implement-rotation-boundary-condition/1947/1 "2022-08-17T20:40:34Z")
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 ---
**Author:** ![julienG](https://yyz2.discourse-cdn.com/flex030/user_avatar/community.freefem.org/julieng/32/222_2.png) [@julienG](https://community.freefem.org/u/julienG)\ **Post date:** [August 18, 2022, 10:01am UTC](https://community.freefem.org/t/is-there-any-way-in-freefem-we-can-implement-rotation-boundary-condition/1947/2 "2022-08-18T10:01:03Z")
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… ---
**Author:** ![zcwang6](https://yyz2.discourse-cdn.com/flex030/user_avatar/community.freefem.org/zcwang6/32/371_2.png) [@zcwang6](https://community.freefem.org/u/zcwang6)\ **Post date:** [August 18, 2022, 1:19pm UTC](https://community.freefem.org/t/is-there-any-way-in-freefem-we-can-implement-rotation-boundary-condition/1947/3 "2022-08-18T13:19:11Z")
Hello Julien, thank you for the answering, would you mind give me some simple examples about this idea? Thank you. ---
**Author:** ![frederichecht](https://yyz2.discourse-cdn.com/flex030/user_avatar/community.freefem.org/frederichecht/32/15_2.png) [@frederichecht](https://community.freefem.org/u/frederichecht)\ **Post date:** [August 20, 2022, 3:45pm UTC](https://community.freefem.org/t/is-there-any-way-in-freefem-we-can-implement-rotation-boundary-condition/1947/4 "2022-08-20T15:45:41Z")
Can you send a real model of your problem, because can have lot of way to modélise a rotating objet. ---
**Author:** ![zcwang6](https://yyz2.discourse-cdn.com/flex030/user_avatar/community.freefem.org/zcwang6/32/371_2.png) [@zcwang6](https://community.freefem.org/u/zcwang6)\ **Post date:** [August 22, 2022, 12:57am UTC](https://community.freefem.org/t/is-there-any-way-in-freefem-we-can-implement-rotation-boundary-condition/1947/5 "2022-08-22T00:57:05Z")
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](https://community.freefem.org/uploads/short-url/aj1mOUUA1pzZ8r4NcI8zwFAA9aY.mesh) (232.5 KB) Thank you ![load](https://canada1.discourse-cdn.com/flex030/uploads/freefem/original/2X/c/c93d953a02206cfa96fed6400c80132a9d08a98f.jpeg) ---
**Author:** ![frederichecht](https://yyz2.discourse-cdn.com/flex030/user_avatar/community.freefem.org/frederichecht/32/15_2.png) [@frederichecht](https://community.freefem.org/u/frederichecht)\ **Post date:** [August 22, 2022, 12:27pm UTC](https://community.freefem.org/t/is-there-any-way-in-freefem-we-can-implement-rotation-boundary-condition/1947/6 "2022-08-22T12:27:57Z")
OK, I static case you can do penalization on rotation boundary normal displacement is zero: like in this example [elas-rot.edp](https://community.freefem.org/uploads/short-url/m3OpDAzo1lqZSE8keK4BphmULwp.edp) (1.4 KB) remark, you can play with boundary condition to see the difference . ---
**Author:** ![zcwang6](https://yyz2.discourse-cdn.com/flex030/user_avatar/community.freefem.org/zcwang6/32/371_2.png) [@zcwang6](https://community.freefem.org/u/zcwang6)\ **Post date:** [August 22, 2022, 12:42pm UTC](https://community.freefem.org/t/is-there-any-way-in-freefem-we-can-implement-rotation-boundary-condition/1947/7 "2022-08-22T12:42:16Z")
Thank you so much Frederic, I think this is exactly what I want.