[yylaw]

I am running 2-pahse flow simulation using ansys fluent.

I tried both steady and transient setting.

1. Transient
After several trials, I set the transient simulation as follow:
For "Fixed" type
Number of time steps: 2e5
Time step size: 1.25e-6s
Max iterations per time step: 25

At the same time I run "Adaptive" type :
Number of time steps: 2e5
Initial time step size: 1.25e-6s
Number of fixed time step: 1s
Minimum time step size: 1e-8s
Maximum time step size: 1s
Max iterations per time step: 100

2. Steady
Cannot converge unless time-step size set smaller than 1e-10, which is nmearly impossible for me to run in such slow computing.

From the volume fraction results, I observed that the flow seem to have "pseudo repetition pattern" at certain period of time. But it may not occur constantly and frequently

My question are :

1. How to determine transient simulation has reached "steady, no change over time" or "pattern over a length of time repeating unconstantly over period" ?

2. Where it starts / How long the 'length of time' that recurring pattern occurs ?

3. How to verify that the "steady/repeat periodic flow" are enough to descirbe the case ?

4. Is there any other way to speed up the calculation process (eg: set time step size much bigger than 1.25e-6, set higher tolerance? but able to converge)?

Any suggestion are welcome. Thank you in advance.

View my previous replies: Transient simulation -> Steady state solution