In computational control, coefficiant of friction (Mu) is considered as zero.

I am working HP steam system. I loaded large models with more than 450 nodes and got the results quickly using program default values for Mu. However, for more realistic results, I changed Mu value to 0.3 (Steel surfaces). This hangs up calculations due to nonconvergence even for a small model with just 55 nodes.

Please let me know:

1. What value of Mu should be taken.
2. How big model is recommended.

Thanks