# 4DFlow Pathline Streamline
**URL:** https://discourse.paraview.org/t/4dflow-pathline-streamline/13124
**Category:** ParaView Support
**Tags:** vtk
**Created:** [October 27, 2023, 11:26am UTC](https://discourse.paraview.org/t/4dflow-pathline-streamline/13124 "2023-10-27T11:26:43Z")
**Posts on this page:** 20
**Page:** 1
### Author:  [@mar.premi](https://discourse.paraview.org/u/mar.premi)
#### Post date: [October 27, 2023, 11:26am UTC](https://discourse.paraview.org/t/4dflow-pathline-streamline/13124/1 "2023-10-27T11:26:43Z")
Hi,
I have .vtk file of a 4DFlow of the blood within the ventricles. I have the velocity field dataset.
I also have these dataset
How can I visualize the pathline and the streamline?
Thank you
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### Author:  [@mwestphal](https://discourse.paraview.org/u/mwestphal)
#### Post date: [October 27, 2023, 11:35am UTC](https://discourse.paraview.org/t/4dflow-pathline-streamline/13124/2 "2023-10-27T11:35:21Z")
please share your data
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### Author:  [@mar.premi](https://discourse.paraview.org/u/mar.premi)
#### Post date: [October 27, 2023, 11:39am UTC](https://discourse.paraview.org/t/4dflow-pathline-streamline/13124/3 "2023-10-27T11:39:38Z")
I have this type of data but for 30 phases.
[1998753RV\_3dflow\_vec\_ph001.vtk](https://discourse.paraview.org/uploads/short-url/dD41JAwcsP7FnjOArGUx3Xy9uWV.vtk) (535.2 KB)
[1998753RV\_3dflow\_volume\_ph001.vtk](https://discourse.paraview.org/uploads/short-url/7etvA3vUZOIHTdUz6omYOWUs0Jl.vtk) (1.4 MB)
[1998753RV\_3dflow\_vline\_ph001.vtk](https://discourse.paraview.org/uploads/short-url/7H60YQ7DIMc41jk8tbHi52THkv.vtk) (804.9 KB)
I have this type of data but for 30 phases
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### Author:  [@mwestphal](https://discourse.paraview.org/u/mwestphal)
#### Post date: [October 27, 2023, 11:42am UTC](https://discourse.paraview.org/t/4dflow-pathline-streamline/13124/4 "2023-10-27T11:42:40Z")
StreamTracer on the Volume data seems to be what you want.
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### Author:  [@mar.premi](https://discourse.paraview.org/u/mar.premi)
#### Post date: [October 27, 2023, 11:47am UTC](https://discourse.paraview.org/t/4dflow-pathline-streamline/13124/5 "2023-10-27T11:47:06Z")
Oh, yes thank you! These are streamlines, right?
But how can I choose the right direction of the tracer arrow?
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### Author:  [@mwestphal](https://discourse.paraview.org/u/mwestphal)
#### Post date: [October 27, 2023, 11:48am UTC](https://discourse.paraview.org/t/4dflow-pathline-streamline/13124/6 "2023-10-27T11:48:05Z")
The streamlines follow the vectors in your data.
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### Author:  [@mar.premi](https://discourse.paraview.org/u/mar.premi)
#### Post date: [October 27, 2023, 11:49am UTC](https://discourse.paraview.org/t/4dflow-pathline-streamline/13124/7 "2023-10-27T11:49:40Z")
but they change if I move the white arrow
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### Author:  [@mwestphal](https://discourse.paraview.org/u/mwestphal)
#### Post date: [October 27, 2023, 11:51am UTC](https://discourse.paraview.org/t/4dflow-pathline-streamline/13124/8 "2023-10-27T11:51:11Z")
Yes, this is how the stream tracer works, it seeds the streamlines from the line. You can choose another type of seed if you want.
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### Author:  [@mar.premi](https://discourse.paraview.org/u/mar.premi)
#### Post date: [October 27, 2023, 11:56am UTC](https://discourse.paraview.org/t/4dflow-pathline-streamline/13124/9 "2023-10-27T11:56:57Z")
Thank you very much, you save me a lot of time. Last thing, is it possible to calculate the viscous energy loss in paraview?
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### Author:  [@mwestphal](https://discourse.paraview.org/u/mwestphal)
#### Post date: [October 27, 2023, 11:58am UTC](https://discourse.paraview.org/t/4dflow-pathline-streamline/13124/10 "2023-10-27T11:58:09Z")
You will need to use the python calculator or programmable filter to do such a specific computation.
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### Author:  [@mar.premi](https://discourse.paraview.org/u/mar.premi)
#### Post date: [October 27, 2023, 12:00pm UTC](https://discourse.paraview.org/t/4dflow-pathline-streamline/13124/11 "2023-10-27T12:00:46Z")
Oh ok so I can directly import the data in Python and calculate the viscous energy loss there.
Thank you very much again
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### Author:  [@mar.premi](https://discourse.paraview.org/u/mar.premi)
#### Post date: [October 30, 2023, 9:02am UTC](https://discourse.paraview.org/t/4dflow-pathline-streamline/13124/12 "2023-10-30T09:02:11Z")
Hey, do you know how can I visualize the pathline instead?
Thank you
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### Author:  [@mwestphal](https://discourse.paraview.org/u/mwestphal)
#### Post date: [October 30, 2023, 9:10am UTC](https://discourse.paraview.org/t/4dflow-pathline-streamline/13124/13 "2023-10-30T09:10:30Z")
What is a `pathline` ? How does it differ from a streamline ?
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### Author:  [@mar.premi](https://discourse.paraview.org/u/mar.premi)
#### Post date: [October 30, 2023, 9:12am UTC](https://discourse.paraview.org/t/4dflow-pathline-streamline/13124/14 "2023-10-30T09:12:06Z")
The streamline follow the velocity field instead the pathline follow the flow
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### Author:  [@mwestphal](https://discourse.paraview.org/u/mwestphal)
#### Post date: [October 30, 2023, 9:14am UTC](https://discourse.paraview.org/t/4dflow-pathline-streamline/13124/15 "2023-10-30T09:14:49Z")
There is only the velocity field on your data, the is no flow field.
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### Author:  [@mar.premi](https://discourse.paraview.org/u/mar.premi)
#### Post date: [October 30, 2023, 9:18am UTC](https://discourse.paraview.org/t/4dflow-pathline-streamline/13124/16 "2023-10-30T09:18:58Z")
But I can see the flow
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### Author:  [@mwestphal](https://discourse.paraview.org/u/mwestphal)
#### Post date: [October 30, 2023, 9:28am UTC](https://discourse.paraview.org/t/4dflow-pathline-streamline/13124/17 "2023-10-30T09:28:17Z")
These are glyphs representing the flow, but the flow data itself is missing from the Volume data you shared.
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### Author:  [@mar.premi](https://discourse.paraview.org/u/mar.premi)
#### Post date: [October 30, 2023, 9:32am UTC](https://discourse.paraview.org/t/4dflow-pathline-streamline/13124/18 "2023-10-30T09:32:30Z")
Ok I understand… Because I use a program call Mass (that merge the flow with the contours) for extract the vtk data.
I can only export these things.
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### Author:  [@mwestphal](https://discourse.paraview.org/u/mwestphal)
#### Post date: [October 30, 2023, 9:36am UTC](https://discourse.paraview.org/t/4dflow-pathline-streamline/13124/19 "2023-10-30T09:36:51Z")
I’m afraid that is a question for Mass, not ParaView.
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### Author:  [@woodscn](https://discourse.paraview.org/u/woodscn)
#### Post date: [November 2, 2023, 10:21pm UTC](https://discourse.paraview.org/t/4dflow-pathline-streamline/13124/20 "2023-11-02T22:21:05Z")
The ParticlePath filter computes pathlines.
For the benefit of anyone interested, streamlines are computed by integrating along a vector field. Pathlines show the path a particle would follow if it were placed in that same vector field. For steady-state vector fields, there is no difference. For time-varying vector fields, this means that you advance the vector field in time as you’re moving the particle along.
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