diffusion convection compressible flow

Gijs

Hi,

we have a mixture with a varying density. We want to calculate the concentration profile of specie A which has the lowest concentration with respect to specie B. If we use the convection diffusion equation of Fluent, the concentration profile is determined by the volume fraction gradient of specie A. Fluent calculates that the smallest volume fraction of specie A is near the inlet point of specie B, as expected. But since the total pressure at the inlet point of specie B is at a maximum, we find that the partial pressure of specie A is highest near the inlet point of specie B, which is counter intuitive (partial pressure of specie A = volume fraction of specie A x total pressure).

Shouldn't we take the pressure gradient also into account in calculating the concentration profile of specie A?

Best regards, Gijs