# How to Compare Pressure Contours from OpenFOAM and ANSYS Fluent Simulations to Generate a Difference Plot?

**URL:** https://discourse.paraview.org/t/how-to-compare-pressure-contours-from-openfoam-and-ansys-fluent-simulations-to-generate-a-difference-plot/17009
**Category:** ParaView Support
**Tags:** openfoam
**Created:** [July 26, 2025, 8:16am UTC](https://discourse.paraview.org/t/how-to-compare-pressure-contours-from-openfoam-and-ansys-fluent-simulations-to-generate-a-difference-plot/17009 "2025-07-26T08:16:19Z")
**Posts on this page:** 2
**Page:** 1

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### Author: ![Mohsin\_Bashir](https://discourse.paraview.org/user_avatar/discourse.paraview.org/mohsin_bashir/32/16793_2.png) [@Mohsin\_Bashir](https://discourse.paraview.org/u/Mohsin_Bashir)
#### Post date: [July 26, 2025, 8:16am UTC](https://discourse.paraview.org/t/how-to-compare-pressure-contours-from-openfoam-and-ansys-fluent-simulations-to-generate-a-difference-plot/17009/1 "2025-07-26T08:16:20Z")

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I ran CFD simulations on the same mesh using both OpenFOAM and ANSYS Fluent. Now, I want to compare the pressure contours by generating a **difference plot** (i.e., `pressure_OpenFOAM - pressure_Fluent`).

### What I Tried:

1. Exported the Fluent results as a **CGNS file** and imported it into ParaView.
2. Loaded the OpenFOAM results directly into ParaView.
3. Used the **Append Attributes** filter to combine the datasets.
4. Applied the **Calculator** filter to compute `pressure_OpenFOAM - pressure_Fluent`.

However, the resulting difference contour appears incorrect. What should i do? I have attached the file to reproduce the case in paraview.  
[reproduce\_case.pvsm](https://discourse.paraview.org/uploads/short-url/azkFoJrtsEzCWXSWrJc0hvvFLTH.pvsm) (566.8 KB)

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<div class="post-metadata">

### Author: ![Mohsin\_Bashir](https://discourse.paraview.org/user_avatar/discourse.paraview.org/mohsin_bashir/32/16793_2.png) [@Mohsin\_Bashir](https://discourse.paraview.org/u/Mohsin_Bashir)
#### Post date: [July 26, 2025, 5:18pm UTC](https://discourse.paraview.org/t/how-to-compare-pressure-contours-from-openfoam-and-ansys-fluent-simulations-to-generate-a-difference-plot/17009/2 "2025-07-26T17:18:32Z")

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Probably i found the answer. [https://youtu.be/jrXS9pohJiI](https://youtu.be/jrXS9pohJiI)  
Let me know if there is a better way to do it.