Variable time stepping method
I am running a transient multiphase flow. If I select variable time stepping method in run calculation, I will have the following settings to adjust.
However, If I selected multiphase flow with explicit solution in models settings I will have.
I have a couple questions regarding this subject
- Both menus shows a Courant Number, what the difference between them and which controls time stepping evolution ?
- Sometimes during in simulation I see a message: Global Courant Number [Explicit VOF Criteria] = 1.498235 for instance. I believe this is not a good solution because Courant Number exceeds 1. In this case, how can I control this Global Courant Number to achieve a value less than 1 ? Should I change Global Courant Number in Variable time stepping or in multiphase model ?
- In the manual is said about variable time stepping that the values of 0.8 and 1.2 for minimum and maximum step change factor respectively is a good value to guarantee a smooth transition for time stepping change. I would like a smoother transition, in this case should I increase minimum step change factor for 1 ?
- What happens if I change Global Courant Number in variable time stepping from 2 to 1 ?
- In summary, in this case when a multiphase model and variable time stepping method is select what is the best way to control solution stability ?
Thanks in advance