Hi,every one:

I try to resolve this type case which simulate the pollutant flowing in the indoor air, and the pollutant diffuses from the building material of indoor that is solid. The diffusion procress is govened by the Fick equations that is similar with one dimensional transient heat conducting equation. My problem is how to couple polluatant diffusion equation for solid with the fluid equation. Thanks in advance for anyone give me some advice.

Hi, you may try modeling scalar transport without reaction or you may use a User Defined Scalar (UDS).

Consider wall as pourous and set appropriate parameters!

Thank you for your response. But how can i got the pollutant diffuse rate from the building material? At the assumption that we have got rate, and how can we couple it with the flowing equation? Thanks you again.