# Gradient visualisations in Paraview

**URL:** https://discourse.paraview.org/t/gradient-visualisations-in-paraview/15163
**Category:** ParaView Support
**Created:** [August 2, 2024, 10:54am UTC](https://discourse.paraview.org/t/gradient-visualisations-in-paraview/15163 "2024-08-02T10:54:28Z")
**Posts on this page:** 7
**Page:** 1

<div class="post-metadata">

### Author: ![akintunde\_akinneye](https://discourse.paraview.org/user_avatar/discourse.paraview.org/akintunde_akinneye/32/13171_2.png) [@akintunde\_akinneye](https://discourse.paraview.org/u/akintunde_akinneye)
#### Post date: [August 2, 2024, 10:54am UTC](https://discourse.paraview.org/t/gradient-visualisations-in-paraview/15163/1 "2024-08-02T10:54:28Z")

</div>

I have the flow over an Ahmed Body in 2D and when I apply the Gradient filter to visualise the vorticity and Q criterion I get these results:

 ![image](https://discourse.paraview.org/uploads/default/original/2X/4/48f15b9501edb486d11e7ecf35800e571a7c25c9.png)

 ![image](https://discourse.paraview.org/uploads/default/original/2X/6/61f10fb0067ff61c1ab85fe6f0e5f748e07d9dd6.png)

 ![image](https://discourse.paraview.org/uploads/default/original/2X/d/d0b4d1a819957d1a416b267673f2cb09529336fe.png)

I am not exactly sure what I’m missing; it seemed pretty straightforward from a tutorial I saw on YouTube.

Any help would be appreciated.

Thanks in advance!

Edit: I tried applying a contour filter and used the Q-criterion as the “Contour-by” and the flow field seemed to vanish.

---

<div class="post-metadata">

### Author: ![cory.quammen](https://discourse.paraview.org/user_avatar/discourse.paraview.org/cory.quammen/32/11193_2.png) [@cory.quammen](https://discourse.paraview.org/u/cory.quammen)
#### Post date: [August 2, 2024, 12:21pm UTC](https://discourse.paraview.org/t/gradient-visualisations-in-paraview/15163/2 "2024-08-02T12:21:11Z")

</div>

Is it possible for you to share your dataset?

---

<div class="post-metadata">

### Author: ![akintunde\_akinneye](https://discourse.paraview.org/user_avatar/discourse.paraview.org/akintunde_akinneye/32/13171_2.png) [@akintunde\_akinneye](https://discourse.paraview.org/u/akintunde_akinneye)
#### Post date: [August 2, 2024, 12:22pm UTC](https://discourse.paraview.org/t/gradient-visualisations-in-paraview/15163/3 "2024-08-02T12:22:34Z")

</div>

That’s fine. I ran the simulation in Openfoam.

Do I just send the state file or do I need to send the results folder?

---

<div class="post-metadata">

### Author: ![cory.quammen](https://discourse.paraview.org/user_avatar/discourse.paraview.org/cory.quammen/32/11193_2.png) [@cory.quammen](https://discourse.paraview.org/u/cory.quammen)
#### Post date: [August 2, 2024, 12:31pm UTC](https://discourse.paraview.org/t/gradient-visualisations-in-paraview/15163/4 "2024-08-02T12:31:24Z")

</div>

The results folder is necessary, and the state file if you wish, though that is less important.

---

<div class="post-metadata">

### Author: ![akintunde\_akinneye](https://discourse.paraview.org/user_avatar/discourse.paraview.org/akintunde_akinneye/32/13171_2.png) [@akintunde\_akinneye](https://discourse.paraview.org/u/akintunde_akinneye)
#### Post date: [August 2, 2024, 12:37pm UTC](https://discourse.paraview.org/t/gradient-visualisations-in-paraview/15163/5 "2024-08-02T12:37:55Z")

</div>

Ok, thanks.

Here is a link to access the folder:

> **[ahmedbody2Dtest2](https://wetransfer.com/downloads/55b88d6bbbfde34c74a452d221d6c52c20240802123550/b538c8)**
>
> 54 files sent via WeTransfer, the simplest way to send your files around the world

---

<div class="post-metadata">

### Author: ![Kenichiro-Yoshimi](https://discourse.paraview.org/letter_avatar_proxy/v4/letter/k/ecc23a/32.png) [@Kenichiro-Yoshimi](https://discourse.paraview.org/u/Kenichiro-Yoshimi)
#### Post date: [August 3, 2024, 11:48am UTC](https://discourse.paraview.org/t/gradient-visualisations-in-paraview/15163/6 "2024-08-03T11:48:14Z")

</div>

The Q criterion and other similar metrics have large absolute values in the boundary layer, but in other areas, they are negligible and do not show up as contour changes. By rescaling to a custom range ![rescale_to_custom_range](https://discourse.paraview.org/uploads/default/original/2X/e/e922a0e0738de71e94e09bc2c5ccfe8749645660.png) and narrowing the range of values, you can observe the contour changes.

 ![q-criterion](https://discourse.paraview.org/uploads/default/original/2X/d/d92e0eb43a1d999f8b9e0b7fa3bc8a0996895286.jpeg)

---

<div class="post-metadata">

### Author: ![akintunde\_akinneye](https://discourse.paraview.org/user_avatar/discourse.paraview.org/akintunde_akinneye/32/13171_2.png) [@akintunde\_akinneye](https://discourse.paraview.org/u/akintunde_akinneye)
#### Post date: [August 5, 2024, 1:31pm UTC](https://discourse.paraview.org/t/gradient-visualisations-in-paraview/15163/7 "2024-08-05T13:31:51Z")

</div>

Thanks for the help!