# Creating equidistant streamlines on a surface
**URL:** https://discourse.paraview.org/t/creating-equidistant-streamlines-on-a-surface/16760
**Category:** ParaView Support
**Created:** [June 1, 2025, 9:06am UTC](https://discourse.paraview.org/t/creating-equidistant-streamlines-on-a-surface/16760 "2025-06-01T09:06:24Z")
**Posts on this page:** 6
**Page:** 1
### Author:  [@scabo](https://discourse.paraview.org/u/scabo)
#### Post date: [June 1, 2025, 9:06am UTC](https://discourse.paraview.org/t/creating-equidistant-streamlines-on-a-surface/16760/1 "2025-06-01T09:06:24Z")
Hi
I have a 3D flow and I want to create equidistant stramlines on a slice. For that i am using the streamtracer function but how can i create streamlines that has constant spacing of streamfunction values? Streamtracer is generating slightly more random streamlines but I want them to be seperated by constant streamfunction values.
Also how can i calculate the streamfunction from the flow?
thanks
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### Author:  [@mwestphal](https://discourse.paraview.org/u/mwestphal)
#### Post date: [June 2, 2025, 12:25pm UTC](https://discourse.paraview.org/t/creating-equidistant-streamlines-on-a-surface/16760/2 "2025-06-02T12:25:33Z")
Use “EvenlySpacedStreamlines2D”, which is a different filter.
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### Author:  [@scabo](https://discourse.paraview.org/u/scabo)
#### Post date: [June 2, 2025, 5:17pm UTC](https://discourse.paraview.org/t/creating-equidistant-streamlines-on-a-surface/16760/3 "2025-06-02T17:17:07Z")
Can you please let me know how to use that because it is not producing anything when i use it on a 2D slice extracted from 3D flow. Also can i calculate the streamfunction in Paraview? I want to plot specific values of streamfunction on the 2D slice.
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### Author:  [@mwestphal](https://discourse.paraview.org/u/mwestphal)
#### Post date: [June 3, 2025, 8:24am UTC](https://discourse.paraview.org/t/creating-equidistant-streamlines-on-a-surface/16760/4 "2025-06-03T08:24:22Z")
Please share your data
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### Author:  [@scabo](https://discourse.paraview.org/u/scabo)
#### Post date: [June 3, 2025, 12:43pm UTC](https://discourse.paraview.org/t/creating-equidistant-streamlines-on-a-surface/16760/5 "2025-06-03T12:43:40Z")
I am asking my supervisor if i can share my data-but can you please let me know if i can calculate the streamfunction from the velocity field of the 3D pipe flow. I want to plot lines of constant streamfunction on a 2D cross-section.
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### Author:  [@otaolafr](https://discourse.paraview.org/u/otaolafr)
#### Post date: [June 5, 2025, 12:18pm UTC](https://discourse.paraview.org/t/creating-equidistant-streamlines-on-a-surface/16760/6 "2025-06-05T12:18:11Z")
maybe i am wrong, but what I do for me and it works:
1. you have slice 1 where you want to do the evenly distributed streamlines (i actually use the inlet patch actually, for this i use extract block instead of slice 1)
2. use slice filter over the filter in 1. (slice 1 or extract block), change its normal so it cuts in a line the filter of 1.) then toggle the advanced options, delete the 0 value, and use add a range of values (button under the “-”) and add eg. 10 points, this is slice 2 and will give you lines
3. do the same as 2. but over the slice 2 in the other remaining direction, this will give you points, this will be slice 3.
4. select your internal mesh which has U vector (if i am not wrong it should be data point type), and use stream line from custom source, then input select the internal mesh filter, and as seed source select the slice 3 filter.
there you go in getting equadistant streamlines