# Pollution exhaust in a garage

**URL:** https://www.simscale.com/forum/t/pollution-exhaust-in-a-garage/85652
**Category:** Project Support
**Created:** [June 12, 2019, 2:50pm UTC](https://www.simscale.com/forum/t/pollution-exhaust-in-a-garage/85652 "2019-06-12T14:50:26Z")
**Posts on this page:** 1
**Showing post:** 4

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### Author: ![tcakir](https://www.simscale.com/forum/user_avatar/www.simscale.com/tcakir/32/23867_2.png) [@tcakir](https://www.simscale.com/forum/u/tcakir)
#### Post date: [June 14, 2019, 5:50am UTC](https://www.simscale.com/forum/t/pollution-exhaust-in-a-garage/85652/4 "2019-06-14T05:50:38Z")

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Hi there,

> [@grosua](#):
>
> First, how did you managed to get the CO concentration in PPM in the sections you posted ??

The T1 passive scalar is set to 1 1/s if you go to the advanced tab. And because scalars are independent regarding unit, they can be interpreted in the way we define them, according to [SimScale Documentation | Online Simulation Software | SimScale](https://www.simscale.com/docs/content/simulation/model/advancedConcepts/passivescalarSources/passivescalarSources.html)

In this case the project poster calculated a uniform distrbution of the CO of 2.77e-8 kg/(m^3 \*s), hence we simply multiply the T1 result with this value and divide by the air mass in 1m^3, and finally multiply with 1000000, to get a mg/kg corresponding with ppm. I loaded the simulation results into paraview and entered “(T1 \* 2.77E-08)/(1.2041) \*1000000” in the calculator. This is the result for the case with the fans:

 ![PNG](https://www.simscale.com/forum/uploads/default/original/3X/a/c/acb64f0ca35bd9ce1acbe4bba736a3cdfe39b5bd.jpeg) Sorry for the different colormapping, but the number seem to be close, let’s wait for the original poster to correct me, if it is not correct.

Below you can see where you find where the flux is defined

 ![afbeelding](https://www.simscale.com/forum/uploads/default/original/3X/4/3/43fa9973593ab22f2ab6aaaf51a252a1802b3818.png)

Hope that answers some of your questions. Regarding the exhaust flow, I think that it is some sort of system, that has some flow rate capability and hence the poster chose that as a boundary condition. However, you could pick any value and see how that helps the overall CO distribution. Which makes this a really cool simulation I think. That’s why I also went ahead and tried to answer your question, because otherwise I would not have seen this project.

Kind regards,  
Tolga

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