Prediction of total time
 

is it possible to predict how long it takes to reach steady state solution in unsteady approach based on the residence time? (my favorite monitors shows constant or periodic shape)

For Example if residence time of a problem is 7*10^-3 [s], and it will be solved unsteady, after how long it will become steady if it has steady state solution.

I know it depends on the initial condition, but I want an estimation for it.
for example if its initial condition is its steady state or if we start from the first point?

I have a problem that is in laminar regime and I think its impossible to solve it in steady state mode, and papers also have unsteady approach, to have convergence. I choose dt=2.5*10^-7 [s] and it becomes converged in each time step (10^-5 for continuity and 10^-7 for velocity), it is 3D and I have started from steady state solution as initial condition. I want to know after how many time steps it becomes steady. I know it has steady state solution.

it is kind of instability flow.

Thank you very much