The Mixing Plane condition is applicable to interior boundaries at the intersection of rotating and nonrotating domains. It models the overall influence of the rotating and nonrotating configurations on the flow field. This is achieved by averaging flow, turbulence and wall distance quantities in the direction of rotation. The condition is available for the Stationary, Frozen Rotor, Wall Distance Initialization, and Mixing Plane Initialization study steps. Typical applications include turbine and compressor simulations in axial and radial flow configurations.

The Mixing Plane condition is suitable for modeling sectors of circular or cylindrical domains, rather than full circular or cylindrical geometries. Modeling multiple stages of turbine or compressor with different pitch angles is possible if the sector angle can accommodate integer multiples of those differing pitch angles. When using the Mixing Plane condition, ensure that Pseudo time-stepping is turned On under the Advanced Settings section in the physics interface. For 3D geometries using High Mach Number Flow interfaces with Mixing Plane condition, ensure that the Mixing Plane Initialization study step precedes a Stationary or Frozen Rotor study step.

From the set of bounding edges to the mixing plane, select an edge where the mixing operation needs to be consolidated. Suitable candidates for such an edge depend on the flow direction. Such candidate edges are highlighted in the image under the section named Flow Direction. Ensure that edges lying along the circumferential direction are not selected for this option. Only a single edge selection is allowed.

Specify the Origin, which acts as the base point for the Axis of rotation and Radial direction vectors. By default, the Origin is set to (0,0,0). Also, specify the Axis of rotation of the rotating domain. It is set to point along the z-axis by default. Additionally, specify the Radial direction, such that it is orthogonal to the Axis of rotation. Ensure that no part of the model geometry lies in the direction opposite to that specified in the Radial direction. It is set to point along the x-axis by default.

Set the Flow direction to Axial or Radial depending on whether the normal component of the flow across the selected interior boundary is predominantly in the axial direction or orthogonal to the axial direction, respectively.

For example, consider a cylindrical rotating domain. The top and bottom, circular, planar surfaces should have Flow direction set to Axial, while the curved surface of the cylinder should have Flow direction set to Radial..