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I want to model a rotatory system (water turbine) with openfoam!
There are two possible methods for modeling a rotatory system (such as a water turbine),

1) using a moving mesh

2) fixing the blades, and rotating the housing employing an angular velocity boundary condition. (fixed grid)

It is clear that the second approach is much easier to implement. I wonder to know their differences? Do they both result in similar results?

Thank you very much,