Convergence in Fluent
 

Hi
I am simulating with ANSYS fluent and in my problems I am working with two phase fluid (CO2 and Acetic Acid) in circular pipes in the shape of serpentine.

I want to know in general when can I say that a simulation is successfully converged?

Is there a range of residuals below which we can say the simulation is converged?
Does these residuals differ from one to another problem and in my case what range of residuals you suggest for convergence
Thanks in advance