2D structure rotate problem

Hi,

The question arises from the model "micromixer_particle tracing" in the Model Gallery. (Rotating Machinery, Laminar Flow)The impeller revolution per time is rotating at 1/s (constant velocity).

Location: Rotating Machinery, Laminar Flow-->Rotating domain-->revolution per time
Expression: 1/s


Could someone explain how change "1/s" to flow rotation rate?

best regards
lee