[Yanyan Huang]

Hi,

I'm new to Fluent, and I met some problems when I use Fluent to simulate the mean age of air.

I first simulate the solid and check the velocity, and then calculate the equation of MAA, but after I calculate the MAA, the velocity in the building became smaller than before, and it seems like the flow was not diffused much from the inlet.

The udf below is used to calculate the mean age of air.

#include "udf.h" 

DEFINE_DIFFUSIVITY(mean_age_diff, c, t, i) 
{ 
return C_R(c,t)*2.88e-05 + C_MU_EFF(c,t) / 0.7; 
} 
DEFINE_SOURCE(mean_age_source, c, t, dS, eqn) 
{
dS[eqn]=0; return C_R(c,t); 
}

All setup is according to the website below.
https://www.computationalfluiddynami...-air-with-cfd/

Thank you for any kind help