Thank you and Yes, I did all as what you guided me, and I got the mass source around 0.25kg/m?-s in each cell according to the X-velocity, then I added this value to mass source and species in Fluent, but when I ran calculation, the solution is not converged. I realized that if I add mass source which is bigger than 0.01 kg/m?-s, the solution of calculation is not converged. What is this problem? Thank you! n