# Free Boundary Condition in Dynamic Modulus

**URL:** <https://forum.itascainternational.com/t/free-boundary-condition-in-dynamic-modulus/318>\
**Category:** FLAC3D\
**Created:** [March 4, 2022, 9:13pm UTC](https://forum.itascainternational.com/t/free-boundary-condition-in-dynamic-modulus/318 "2022-03-04T21:13:55Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![CrissBidermann](https://avatars.discourse-cdn.com/v4/letter/c/43a26b/32.png) [@CrissBidermann](https://forum.itascainternational.com/u/CrissBidermann)\
**Post date:** [March 4, 2022, 9:13pm UTC](https://forum.itascainternational.com/t/free-boundary-condition-in-dynamic-modulus/318/1 "2022-03-04T21:13:55Z")

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Is it possible to apply the “zone dynamic free-field on” command on a cylindrical geometry? What should I do if I get the following error: “No boundary faces on vertical plane”?

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**Author:** ![cheng](https://avatars.discourse-cdn.com/v4/letter/c/ecccb3/32.png) [@cheng](https://forum.itascainternational.com/u/cheng)\
**Post date:** [March 4, 2022, 9:30pm UTC](https://forum.itascainternational.com/t/free-boundary-condition-in-dynamic-modulus/318/2 "2022-03-04T21:30:23Z")

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Unfortunately, the short answer is “no”.  
The side faces of your model must be parallel to the z-direction.