# Animate StreamTracer maximum length in conjunction with Extractor

**URL:** https://discourse.paraview.org/t/animate-streamtracer-maximum-length-in-conjunction-with-extractor/8071
**Category:** ParaView Support
**Created:** [September 23, 2021, 9:09pm UTC](https://discourse.paraview.org/t/animate-streamtracer-maximum-length-in-conjunction-with-extractor/8071 "2021-09-23T21:09:19Z")
**Posts on this page:** 3
**Page:** 1

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### Author: ![Nicholas\_Yue](https://discourse.paraview.org/user_avatar/discourse.paraview.org/nicholas_yue/32/5203_2.png) [@Nicholas\_Yue](https://discourse.paraview.org/u/Nicholas_Yue)
#### Post date: [September 23, 2021, 9:09pm UTC](https://discourse.paraview.org/t/animate-streamtracer-maximum-length-in-conjunction-with-extractor/8071/1 "2021-09-23T21:09:19Z")

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Hi,

Is there a way to animate the length of the StreamTracer so that as part of the Extractor output, it grows in length i.e. for every frame exported, the streamline grows longer?

Maybe some python snippet I can associate with Extractor to vary the length?

I am trying to illustrate the flow around objects and the length of the stream line helps me convey that message.

 ![Paraview_Grow_StreamTracer](https://discourse.paraview.org/uploads/default/original/2X/c/cbd3001dbdb07d5405ed3828a62b355363cf2f56.png)

Cheers

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### Author: ![mwestphal](https://discourse.paraview.org/user_avatar/discourse.paraview.org/mwestphal/32/17_2.png) [@mwestphal](https://discourse.paraview.org/u/mwestphal)
#### Post date: [September 24, 2021, 7:20am UTC](https://discourse.paraview.org/t/animate-streamtracer-maximum-length-in-conjunction-with-extractor/8071/2 "2021-09-24T07:20:12Z")

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Is your dataset temporal ?

In any case, see this webinar:

[![](https://discourse.paraview.org/uploads/default/original/2X/7/7ae9a91a1ff3b108a0e6f362ad713d29d9a9174c.jpeg "Kitware ParaView Streamlines Webinar") ](https://www.youtube.com/watch?v=7WMaHXLK6No)

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<div class="post-metadata">

### Author: ![Nicholas\_Yue](https://discourse.paraview.org/user_avatar/discourse.paraview.org/nicholas_yue/32/5203_2.png) [@Nicholas\_Yue](https://discourse.paraview.org/u/Nicholas_Yue)
#### Post date: [September 24, 2021, 3:32pm UTC](https://discourse.paraview.org/t/animate-streamtracer-maximum-length-in-conjunction-with-extractor/8071/3 "2021-09-24T15:32:44Z")

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Thank you @mwestphal , the webinar gave me more ideas to ponder.

I downloaded my dataset from an OpenFOAM simulation though it appears to have only a single time step in the data. I will now look for richer temporal dataset and apply the technique describe in the webinar.

Cheers