Steady VS Unsteady
 

Hello

So I did a simulation with steady model of a laminar forced convection flow with
Segregated flow, Steady

But when I'm trying to get same result with unsteady models like coupled flow (or segregated), implicit , .... the result is totally different. You should be able to get same result. Like if the boundary conditions are not changing, same results should be obtained over time and you should reach to the steady state.

where is the problem??!!!

Are you performing temporal averaging and comparing that field to the steady result?


The results will not be identical, in any case.

I am not doing any averaging on the data. But even doing averaging shouldn't change anything since the flow is steady.

The results should be the same since the flow is steady. If you use an unsteady model for a steady flow, as the time goes on, the steady state should be reached.

Is the unsteady case producing an unsteady result?

You could make it more steady-like by increasing the timestep a lot.

It's weird. After couple of time steps, the solution is not changing.
Definitely it's not the steady state because it is different with the result obtained by steady model.

Is the steady case even producing a steady result? Most of the time, it doesn't.

Regardless, I wouldn't expect always the same result. They can be different.