A given simulation can make use of multiple domain interfaces. Each Fluid Fluid interface can use a different frame change model. For example, two domains can be connected by a Fluid Fluid interface without a frame change; one of these domains might also contain a rotationally periodic interface to define a blade passage. Finally, there might be another Fluid Fluid interface between the first two domains and a third domain that uses a frame change model. A four stage axial compressor, consisting of four stators and four rotors, might contain seven Fluid Fluid interfaces with a Frozen Rotor frame change model (one at each frame change interface between components).

It is possible to have a combination of frame change models within a single problem definition. For example, in a stator/rotor/stator configuration, the first Fluid Fluid interface could be a Stage or Frozen Rotor interface, and the second interface could be a Transient Rotor-Stator interface. This might make sense if you are only interested in accounting for the transient conditions between the rotor and the downstream stator.