Use a rotating-frame approach when a steady approximation of rotation is sufficient. Use sliding mesh when relative motion, blade passing, wake interaction or time-resolved loads are part of the engineering question.
What a rotating reference frame gives you
A rotating-frame formulation represents rotation through the governing equations while the mesh remains stationary relative to its region. This is efficient for many steady operating-point calculations and is often a strong first model for fans, pumps and turbomachinery.
What sliding mesh adds
Sliding mesh physically changes the relative angular position of connected mesh regions over time. That allows transient rotor-stator interaction, blade passing, wake transport and periodic load fluctuations to be resolved, at the cost of transient time marching and interface-resolution requirements.
Choose from the required output
If the goal is mean pressure rise, torque or efficiency at a steady operating point, begin with the less expensive steady rotating-frame model when its assumptions are defensible. If phase-dependent pressure, acoustic forcing, cyclic loads or transient interaction matters, use sliding mesh.
Match angular and temporal resolution
A sliding-mesh result is only as good as its timestep and interface resolution. Select timestep from rotational speed and desired angular advance, then verify timestep sensitivity. Keep compatible mesh resolution across the moving interface and monitor conservation.
Use the two models as a hierarchy
A practical workflow is to converge a steady rotating-frame case first, use it for initialization and screening, then promote selected operating points to sliding mesh. Differences between the mean sliding-mesh result and the steady model quantify the importance of rotor-stator interaction.
Run the engineering check
Use the linked Abecator calculator or workflow to turn the setup decision into a quantitative check.
Continue the Abecator path
- Rotating-Mesh Time-Step Calculator
- Technical Case: Rotating Interface Problems
- Turbomachinery CFD Training
- Gas Turbine & Turbomachinery CFD Consulting
Primary Siemens reference
STAR-CCM+ is a Siemens product name. Abecator is independent and this article is original engineering guidance; it does not reproduce Siemens documentation or third-party tutorial text.