Initial CO concentration is canceled out if I add other sources of CO.

[javiercarlos]

Good evening,

I have a problem. I have defined Init Region so that the entire parking lot has a concentration of 50 ppm of CO, and when I run the simulation, it looks fine, as shown in the image, with the entire plane colored red symbolizing 50 ppm. As the wind blows, the pollution decreases and takes on greener or bluer colors. However, if I want to add small obstructions in the parking lot that simulate cars emitting CO, when I run the simulation again, the INIT REGION is canceled, the graph shows a BLUE plane (clean air), and the small obstructions emitting CO. How can I make the small obstructions add CO to the scenario and not override the INIT REGION (initial concentration of 50 ppm of CO)?

This image shows what happens when I only have the INIT REGION set to 50 ppm of CO (initial air condition with a CO concentration of 50 ppm). But when I add other obstructions that emit CO, the init region is canceled out and the scenario is shown as if everything were pure air.

[drjfloyd]

Please provide an input file.

[javiercarlos]

Thank you very much for your reply,

As you can see, it only takes 1.3 seconds, and the entire parking lot is displayed, as if there were no INIT REGION = 50 ppm of CO. This happened after I added:

1. 4 obstructions (CO2, CO8, CO11, CO13),
2. Then create a Simple Chemistry reaction and add Carbon Monoxide.
3. Then I created a surface called “COemission” of the General type, with the following configuration (Specify Mass Flux of individual species), and in the Species injection section, I set Carbon Monoxide = 1.156E-3
4. And finally, I assigned that surface to the upper faces of the 4 obstructions (CO2, CO8, CO11, CO13).

What I am trying to do is start the entire parking lot with a CO concentration of 50 ppm, and add 4 obstructions that each emit carbon monoxide (simulating cars).

I appreciate your help, thank you very much.

Translated with DeepL.com (free version)

[drjfloyd]

&REAC FUEL='CARBON MONOXIDE'/

This input is telling FDS you want to burn CO to CO2 anytime there is O2 present. At 50 ppm there is plenty of O2 in the atmosphere to convert all 50 ppm of CO to CO2. What you want is to just have CO as a tracked species:

&SPEC ID='CARBON MONOXIDE'/

[javiercarlos]

Thank you, I was able to correct it.