Rapid Divergence
 

I am a starting user of FLUENT. Now when I start iteration, there are always 'Rapid divergence detected..' I cannot understand this because I just changed inlet mole fraction of 4 gases. It never occurred before. So is there any body who has good idea? Please help me.

Re: Rapid Divergence
 

Check if your residuals are scaled or not in the solve - monitor - residuals menu. If they aren't scaled that explain your error message.

If they are scaled, try to lower your underelaxation factor for mass fraction and continuity/velocities.

Best regards