Learning Forum

[Bill Hsu]

Hello everyone,

I tried to use an air conditioner and an air purifier to dilute the particles in a room, I set 2400 particles uniformly distributed in the room initially, and used a UDF to calculate the concentration. I set the escape condition for two outlets and the trap condition for walls. The simulation was carried out for 60 minutes (transient and unsteady particle tracking), and I calculated the particle concentration every 5 minutes. Here are my questions:

1. I expected that the particle concentration would decrease as time passed (because the particle will escape from the domain and trap on the wall), but the particle concentrations at every timestep are the same as the initial concentration, it seems that my UDF only considers the initial total particle mass, how do I adjust my code?

2. The number of particles tracked decreased as time passed, and the escaped and trapped information didn't show up. Is it a common situation?

The attached picture is my UDF:

[Supreetha J]

Hello Bill,
Kindly refer to this Forum discussion Problems of DPM concentration UDF (ansys.com)
You can either enable two way coupling or write UDF.
Thank you.