stator-rotor interaction with different blade count
 

Hi everybody
I hope this thread is posted in the correct forum. I am very new to the CFD community.
I am intending to simulate a turbine stage with stator-rotor interaction. I know that there are different approaches (frozen rotor, mixing plane and unsteady sliding grid approach). My question is how that I can account for the fact that the stator and rotor have a different blade count without having to create the entire geometry. Ideally I only want to model one blade each.
The simulation will be a transient simulation where I intend to use URANS. Has anybody done a similar case or knows where I find these information or appropriate tutorials for it?
I have seen option in CFX where a phase lad is used (time transformation). Is something like this available in OpenFoam?

Many thanks