[aja1345]

Hi,

I am simulating a turbine. But I don't know that how use these URF.

First, I decrease URFs but When is the best time to increae Under-Relaxation factors?

Thanks.

[hwet]

If you think your simulation is stable you can increase them.

[aja1345]

Originally Posted by hwet

If you think your simulation is stable you can increase them.

Thanks

What is the exact meaning of stable here?

[LuckyTran]

Originally Posted by aja1345

Thanks

What is the exact meaning of stable here?

It means if your simulation doesn't diverge or is otherwise marginally divergent. You should always use the highest URFs as long as it doesn't cause your simulation to diverge, reducing them only if you have stability problems and then increasing them back to their defaults if possible. The defaults are generally optimal, but you can achieve faster convergence by increasing the URFs above their defaults.