Time marching transient simulation towards steady state to get cl and cd
 

Hello Everyone
I am trying to get the cl and cd values for an airfoil, but when I run the airfoil in steady mode, there is no convergence. I have come to realise that this is because there are vortices in the wake of the airfoil, lending a highly unsteady nature to the flow. So i am trying to run the airfoil in unsteady mode and march the solution towards a steady state.
How do I know if the solution has reached a steady state? right now I am monitoring the cl value and waiting until it becomes independent across 5-6 timesteps. Is this the right method to do so?

Any help will be hugely appreciated.
Also the airfoil is a custom optimised one and hence I have no reference values to cross-check.

NonStopEagle