Large eddy simulation (LES) is not compatible with the mixing plane model for rotating machinery. Generally, LES is not compatible with the mixing plane model because they are two conflicting models. LES resolves unsteady flow features, and the mixing plane model averages, or mixes out, flow features. In both Fluent and CFX, however, there is nothing preventing the user from running LES together with the mixing plane model. The lack of a limitation is not an oversight, and there is a reason it is not prevented. Certain modeling tricks can be performed when LES is used while mixing plane is active in a multi-stage simulation. For example, imagine we have a 3 stage compressor. Our interest is mainly in the last stage, and we want to resolve flow features and account for unsteady flow interaction between the last two blade rows. We can model the last stage with a sliding mesh, while the other stages are modeled via mixing plane or MRF. We may also want to use LES to better model flow in the last stage. What takes place near the mixing plane region is not important as far as LES is concerned, but including the front stages with a mixing plane will provide better and more accurate conditions at the inlet to the last stage than modeling the configuration without them. So while the documentation states LES and mixing plane models are not compatible (which is true), it may be desirable to turn LES on while mixing plane is used under specific circumstances, such as in the example above, in order to reduce computational costs.