# Evaluation of a volume integral over a 2D plane

**URL:** https://discourse.paraview.org/t/evaluation-of-a-volume-integral-over-a-2d-plane/11488
**Category:** ParaView Support
**Created:** [February 24, 2023, 5:01pm UTC](https://discourse.paraview.org/t/evaluation-of-a-volume-integral-over-a-2d-plane/11488 "2023-02-24T17:01:16Z")
**Posts on this page:** 1
**Page:** 1

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### Author: ![Captain\_Convergence](https://discourse.paraview.org/letter_avatar_proxy/v4/letter/c/e19b73/32.png) [@Captain\_Convergence](https://discourse.paraview.org/u/Captain_Convergence)
#### Post date: [February 24, 2023, 5:01pm UTC](https://discourse.paraview.org/t/evaluation-of-a-volume-integral-over-a-2d-plane/11488/1 "2023-02-24T17:01:16Z")

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Dear support,

I need to evaluate the following volume integral over a 2D surface obtained using the threshold filter:  
 ![image](https://discourse.paraview.org/uploads/default/original/2X/5/5ec9358ddfb8d24208f314a77d45d15e76c11f5d.png)

I have already obtained the **divergence of f\_vw** term and the only thing left is to integrate this expression. I have noticed that **for another variable like density (rho)** (which changes between 0.25 and 0.35), I have an integral value of **0.00707796** which is way lower from what I would expect, you have here the contour with the legend:

 ![rho_field](https://discourse.paraview.org/uploads/default/original/2X/0/0dd1973a4425666b17f0b90c74c6d3a6f7e02b15.jpeg)

I am using the `IntegrateVariables` filter and I guess that it is that low because the data is 2D (no Y dimension). Is there any better way to obtain 2D integral values?

Thank you in advance!