Criteria and delta?
 

Does anyone knows that how EFD calculates convergence criteria and delta?

The criteria is based on many factors and automatically defined after one travel. The algorithm to determine them uses these factors (for example mesh/cell size, convergence behavior etc.) to not get too fine criteria with a very coarse mesh otherwise you will not reach convergence since the fluctuations due to coarse mesh are too big. The algorithm itselfe is only known to the developers.
You can however define the criteria manually in the calculation control options either before or during the calculation, they will take effect with the next iteration.

The delta is the difference over the minimum and maximum values in the analysis interval.

I hope this helps you,
Boris

Yes, thank you ..