# Rotating direction for streamlines out from line source?

**URL:** https://discourse.paraview.org/t/rotating-direction-for-streamlines-out-from-line-source/16608
**Category:** ParaView Support
**Created:** [May 14, 2025, 12:35am UTC](https://discourse.paraview.org/t/rotating-direction-for-streamlines-out-from-line-source/16608 "2025-05-14T00:35:14Z")
**Posts on this page:** 4
**Page:** 1

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### Author: ![Devin\_Richard\_Bayly](https://discourse.paraview.org/user_avatar/discourse.paraview.org/devin_richard_bayly/32/5533_2.png) [@Devin\_Richard\_Bayly](https://discourse.paraview.org/u/Devin_Richard_Bayly)
#### Post date: [May 14, 2025, 12:35am UTC](https://discourse.paraview.org/t/rotating-direction-for-streamlines-out-from-line-source/16608/1 "2025-05-14T00:35:15Z")

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Hi there,

I’m trying to make some stream lines that resemble air velocity within a volume, but I’m struggling to get the streamlines to leave the source line in the right direction. It seems like they sort of randomly pick an orthogonal angle to my source line, and flow out from there, but mostly this doesn’t work to resemble airflow proceeding from the line widget, in the direction I’ve annotated on the screenshot.

 ![image](https://discourse.paraview.org/uploads/default/original/3X/4/b/4b9a188dd3b8b2fe65d469af506366ef03398626.png)  
Here’s what seems to happen as I pick some other orientations. Things seem to mostly flow, from “left to right” despite what I try to do, when I’m more looking for “top to bottom” in the context of these images.  
 ![image](https://discourse.paraview.org/uploads/default/original/3X/2/5/257e82ee19fab236c097c87a4a52b35d6f5f06b6.png)  
 ![image](https://discourse.paraview.org/uploads/default/original/3X/7/e/7e32c64015f9443b2aec39d7025c052a013a2a90.jpeg)

Is my main recommended approach to transform (rotate) the input data until the streamlines go in the direction I’m looking for? Or is there a way to change the orthogonal angle the streamlines have leaving the line source?

Thanks so much!

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### Author: ![Devin\_Richard\_Bayly](https://discourse.paraview.org/user_avatar/discourse.paraview.org/devin_richard_bayly/32/5533_2.png) [@Devin\_Richard\_Bayly](https://discourse.paraview.org/u/Devin_Richard_Bayly)
#### Post date: [May 14, 2025, 12:53am UTC](https://discourse.paraview.org/t/rotating-direction-for-streamlines-out-from-line-source/16608/2 "2025-05-14T00:53:22Z")

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wait, I think my question is off. The direction has to do with the vector field, I think this might mean the x component of the velocity is getting mistaken for y, I’ll use the calculator to fix.

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### Author: ![wascott](https://discourse.paraview.org/letter_avatar_proxy/v4/letter/w/8e8cbc/32.png) [@wascott](https://discourse.paraview.org/u/wascott)
#### Post date: [May 14, 2025, 1:04am UTC](https://discourse.paraview.org/t/rotating-direction-for-streamlines-out-from-line-source/16608/3 "2025-05-14T01:04:03Z")

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Devin,  
I think you are correct having to do with your vector fields. I created a tutorial for CDF that may cover some of what you are asking for. In ParaView, see Help/ Classroom Tutorials/ Targeted Computational Fluid Dynamics, and one of the flow in a field examples.

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### Author: ![Devin\_Richard\_Bayly](https://discourse.paraview.org/user_avatar/discourse.paraview.org/devin_richard_bayly/32/5533_2.png) [@Devin\_Richard\_Bayly](https://discourse.paraview.org/u/Devin_Richard_Bayly)
#### Post date: [May 14, 2025, 1:16am UTC](https://discourse.paraview.org/t/rotating-direction-for-streamlines-out-from-line-source/16608/4 "2025-05-14T01:16:38Z")

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Thanks yea, I swapped x and y and the lines started going in the direction I wanted, now I have to troubleshoot why the nvidia paraview index plugin is rendering the volume outside the “outlined” extent… sigh I’ll tackle that tomorrow  
haha