# Creating smooth flow extensions

**URL:** <https://discourse.slicer.org/t/creating-smooth-flow-extensions/23197>\
**Category:** VMTK\
**Created:** [April 29, 2022, 4:28pm UTC](https://discourse.slicer.org/t/creating-smooth-flow-extensions/23197 "2022-04-29T16:28:10Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![JuliaW](https://avatars.discourse-cdn.com/v4/letter/j/bb73d2/32.png) [@JuliaW](https://discourse.slicer.org/u/JuliaW)\
**Post date:** [April 29, 2022, 4:28pm UTC](https://discourse.slicer.org/t/creating-smooth-flow-extensions/23197/1 "2022-04-29T16:28:10Z")

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Dear vmtk community,

Currently, I am preparing a segmented aorta for flow analysis.  
Using vmtk I have cut open the surface and added flow extensions.  
However, at opening of the aorta, the transition between the flow extension and the segmented surface is not smooth (see the attached image).  
Is there a way to smooth out the edges?  
Maybe I could refine the mesh of the flow extensions, but I wouldn’t know how.

Thank you for your reply!

Kind regards,

Julia

 ![Flow_extension aorta_arrows](https://us1.discourse-cdn.com/flex002/uploads/slicer/original/3X/6/4/643d0df0db75dca52c0300f29996adcebd88cda3.jpeg)

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**Author:** ![lassoan](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/lassoan/32/13_2.png) [@lassoan](https://discourse.slicer.org/u/lassoan)\
**Post date:** [April 29, 2022, 4:38pm UTC](https://discourse.slicer.org/t/creating-smooth-flow-extensions/23197/2 "2022-04-29T16:38:02Z")

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Probably the simplest is to edit the mesh locally to smooth out that edge in Meshmixer (BubbleSmooth brush) or 3D Slicer (Segment Editor, Smoothing effect, use the brush in slice or 3D views).