# HOW to Smooth the fluid interface？
**URL:** https://discourse.paraview.org/t/how-to-smooth-the-fluid-interface/11737
**Category:** ParaView Support
**Created:** [March 28, 2023, 12:20pm UTC](https://discourse.paraview.org/t/how-to-smooth-the-fluid-interface/11737 "2023-03-28T12:20:25Z")
**Posts on this page:** 5
**Page:** 1
### Author:  [@AlexL](https://discourse.paraview.org/u/AlexL)
#### Post date: [March 28, 2023, 12:20pm UTC](https://discourse.paraview.org/t/how-to-smooth-the-fluid-interface/11737/1 "2023-03-28T12:20:25Z")
I used the S-ALE method of LS-DYNA to study an underwater bubble and use the DominationGroup option of the threshold filter to distinguish between bubble and water. However, due to the presence of meshes, the bubble interface is very rough. Now I want to make the bubble interface smooth. How can I do this?
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### Author:  [@AlexL](https://discourse.paraview.org/u/AlexL)
#### Post date: [March 28, 2023, 12:22pm UTC](https://discourse.paraview.org/t/how-to-smooth-the-fluid-interface/11737/2 "2023-03-28T12:22:00Z")
I’m new at Paraview, hoping your reply.THANKS!
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### Author:  [@Kenneth\_Moreland](https://discourse.paraview.org/u/Kenneth_Moreland)
#### Post date: [March 28, 2023, 2:24pm UTC](https://discourse.paraview.org/t/how-to-smooth-the-fluid-interface/11737/3 "2023-03-28T14:24:31Z")
There is not a straightforward way to smooth the mesh boundary (AFAIK), but you might be able to create a smoother mesh by using something other than `Threshold`.
Does your simulation output volume fractions for each material/group? If so, you can use the `Cell Data To Point Data` filter to average the data to the points and then use `Contour` (or `Clip` with a `Clip Type` of `Scalars`) to find the interface. The act of averaging cell data to point data will have a smoothing effect.
If you don’t have volume fractions, you can do the same thing with your `DominantGroup` field _as long as you only have 2 groups_. If you have more than 2 groups, the `Cell Data To Point Data` is going to give invalid values. If that is the case, you can use the `Calculator` filter to make a field that is either 0 or 1 depending on whether the `DominantGroup` is a particular value. For example, to create this field for group id 2, use the calculator expression `if(DominantGroup = 2, 1, 0)`.
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### Author:  [@AlexL](https://discourse.paraview.org/u/AlexL)
#### Post date: [March 28, 2023, 2:28pm UTC](https://discourse.paraview.org/t/how-to-smooth-the-fluid-interface/11737/4 "2023-03-28T14:28:32Z")
Thank you! I’ll try the method you mentioned.
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### Author:  [@AlexL](https://discourse.paraview.org/u/AlexL)
#### Post date: [March 28, 2023, 2:53pm UTC](https://discourse.paraview.org/t/how-to-smooth-the-fluid-interface/11737/5 "2023-03-28T14:53:07Z")
I tried the first method you mentioned.It did work, but didn’t perform well enough. How can I further make the interface smoother? Should Smooth Filter be used?
My goal is not to display the inside of the bubble, but only to display water while making the water-
gas interface smoother.
