Yes! I checked the residual already, then I realized that the reason why the solution is not converged is because of a species residual line. In the residual criteria, if I increase the residual value by double the default number (0.001) provided by Fluent, so the solution is converged. But I am curious that if I increase that residual number of a species from 0.001 to 0.002, will the solution be wrong (even it is converged)? Thank you! n