Steady solution from Transient simulations
 

Hi Everybody,

I am trying to figure out how to determine that a transient simulation is actually reaching steady state.
I understand that in a steady state simulation, if the solution converged, a steady state solution is reached. However, in transient simulations, a converged solution implies that a solution for the time step is reached. But how do we know whether the solution is steady state ?

Thanks ...

Well, if your problem has a steady state and if each of your time steps are converging, then you should reach a steady state after certain number of time steps.

Now there can be many ways to determine what a steady state is. The idea is that you need to define a criteria to determine a steady state. Say for example, you can say that if the change in velocity is less than 0.1% in 10 time steps, you will consider that a steady state is reached.

So basically you need to define a criteria for steady state ( or a norm for determining when a steady state is reached).

Now depending upon your exact need you will have to work on the complexity of the criteria. But in general, as a first step, you can just see the output at different time steps and just visually call it a steady state when you find that the solution is not changing appreciable with time.

Hi simulationman,

Thanks for your prompt reply,
Would it be possible to tell me how to obtain a live update of some of the simulation results in a 3D transient simulations in Fluent 12.1 ?

Thanks ...