Species Diffusion on boundary
 

Hi everyone.
I am simulating a diffusion flame using Eddy break up. Instead of a burner I have a circular surface where I have the mass flow rate necessary for the pretended combustion power.

The problem that I have is that for low combustion powers like 50kw I prescribe a mass flow of 1E-3 kg/s, however on the plane just above the burner, I have a mass flow rate of fuel of 8E-3 kg/s. I assumed that was from the flow boundary diffusion on the segregated species. However, if I turn it off, the mass flow is correct (above the burner the mass flow is bellow 1E-3 kg/s), however I cannot converge the energy equation, since he always limits the minimum temperature on the edge of the burner surface.

Has anyone ever had this problem simulating diffusion flames??

Thanks