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[FAQ]

A: In ANSYS CFX, during transient rotor-stator runs, the meshes of rotating frames remain stationary, but the relative position of the flow profiles at the 2 sides of a transient rotor-stator interface is updated each time step. The forces and moments which are calculated with expressions like force_x() or torque_x() are therefore calculated in the relative frame of the rotating parts. To get the forces and moments in absolute frame, a coordinate transformation is needed. If for instance the Z axis is the axis of rotation, the forces in X and Y direction ca be expressed as:
myForceXabs = force_x()@Impeller * cos(Angular Velocity * Time) + force_y()@Impeller * sin(Angular Velocity * Time), myForceXabs = -1 * force_x()@Impeller * sin(Angular Velocity * Time) + force_y()@Impeller * cos(Angular Velocity * Time).
Similarly, moments in absolute frame can be transformed in the same way.