Using Frozen Rotor for Solving Rotating Analyses

Frozen Rotor is an optional setting for rotating analyses that reduces simulation time and produces an approximate solution. Unlike a traditional rotating analysis, the rotating region does not rotate during the simulation. Rotation and associated momentum terms are imparted to the flow, however.

Frozen Rotor is useful for quickly simulating rotating devices without the complexity of numerically rotating the physical rotor. Note that Frozen Rotor does not predict interaction between rotating and non-rotating objects (such as rotor-stator or impeller-volute).

Frozen Rotor analyses are generally faster because Autodesk® CFD does not update the rotating mesh position and the sliding rotor-stator interface with every time step. Because the rotor is static, you can use larger time steps which lead to a steady-state solution in less time.

Setup considerations

• Construct the analysis model geometry using the same geometric guidelines as for a traditional rotating region analysis.
• Use a larger time step than you would in a traditional rotating analysis. In fact, you can use the largest time step that maintains stability.
• As with traditional rotating analyses, we recommend ramping up the rotational speed to avoid impulsive starts.
• To enable Frozen Rotor, enable this flag in the Flag Manager: FrozenRotor