# Tutorial on 3D geometries

**URL:** <https://fenicsproject.discourse.group/t/tutorial-on-3d-geometries/7140>\
**Category:** dolfinx\
**Created:** [November 22, 2021, 11:00am UTC](https://fenicsproject.discourse.group/t/tutorial-on-3d-geometries/7140 "2021-11-22T11:00:11Z")\
**Posts on this page:** 2\
**Page:** 2

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**Author:** ![E\_P](https://yyz2.discourse-cdn.com/free1/user_avatar/fenicsproject.discourse.group/e_p/32/1356_2.png) [@E\_P](https://fenicsproject.discourse.group/u/E_P)\
**Post date:** [November 10, 2024, 2:35pm UTC](https://fenicsproject.discourse.group/t/tutorial-on-3d-geometries/7140/21 "2024-11-10T14:35:07Z")

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Many thanks.

Time-dependent boundary conditions used to be expressed by expression function in the old fenics, assume, it should be somewhat different, right? is there any fresh example in new fenicsx?

Thanks,

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**Author:** ![dokken](https://yyz2.discourse-cdn.com/free1/user_avatar/fenicsproject.discourse.group/dokken/32/1560_2.png) [@dokken](https://fenicsproject.discourse.group/u/dokken)\
**Post date:** [November 10, 2024, 3:02pm UTC](https://fenicsproject.discourse.group/t/tutorial-on-3d-geometries/7140/22 "2024-11-10T15:02:54Z")

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There is a large variety of examples, see for instance  
[https://jsdokken.com/dolfinx-tutorial/chapter2/ns\_code2.html#boundary-conditions](https://jsdokken.com/dolfinx-tutorial/chapter2/ns_code2.html#boundary-conditions)  
and there are plenty of posts on the forum about this, for instance [Time-stepping of nonlinear time dependent problem with time-dependent BC - #8 by francesco-ballarin](https://fenicsproject.discourse.group/t/time-stepping-of-nonlinear-time-dependent-problem-with-time-dependent-bc/15919/8)

Please note that your question is off-topic to the initial question, and should first warrant a search of the vast amount of posts on this forum to check if it has been asked before. I’ll be nice this time, and answer it fully, but if this behavior is repeated the post will be removed.

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