False time step factors

Jesper Laursen

Hi everybody!

I am using false time step factors for calculating unsteady 3D multi-fluid flow in a wwtp aeration tank. I am using false time step factors to avoid numerical instability. My problem is that I can´t find any good definition of what false time steps exactly do, or how it works. The CFX 4.4 manual doesn't give any usefull information on that point. Can anyone give me a thorough description of how it works? -Or do anybody know any good articles on the subject? Are there any drawbacks in using false time step factors in the problem described above?

Thanks in advance Jesper, a student from Denmark.