simulate pollutant concentration
 

I want to ask CFX expert on how to simulate concentration using K-Epsilon model in a street at level z=0 using a line source . the mass flow rate is 0.01 kg/s.
thanks

You cannot use lines for sources. Either use a series of points or define a long skinny volume.

why we can't use a little surface named source parts and apply boundary condition ?

Yes, you can define a source on a surface/interface/boundary as well.