SimScale does not currently support free fluid‑driven rotation where the solver computes the rotor RPM from aerodynamic torque. In CFD, rotating machinery is simulated using prescribed rotation : MRF rotating zone – steady-state performance sweep at a fixed RPM. Sliding mesh (AMI) – transient simulation with a prescribed rotational speed. Both approaches require the user to define the rotational velocity. The solver does not solve for RPM from aerodynamic torque. Recommended workflow for your case: Run a series of CFD simulations at different RPM values. Use Result Control → Forces and Moments to extract aerodynamic torque. Plot torque vs RPM . The natural operating RPM is where aerodynamic torque ≈ load torque (or zero net torque for a free-running rotor). This is the standard approach for wind turbines and similar rotors when the operating speed is unknown. Also note: the Rotating Motion boundary condition exists only in structural analyses (Static, Dynamic, Thermomechanical), not in CFD. So the practical method is a parametric RPM sweep , not a self-accelerating rotor simulation. Here are a few SimScale resources that explain the workflow used for turbines and rotating machinery. 1. Wind turbine setup with rotating zones (MRF) Shows how to prepare the CAD and define a rotating zone with a prescribed RPM. simscale.com Example 2: Wind Turbine (SimScale) - How to Prepare the CAD for Simulating... When performing a simulation with rotating parts, such as pumps and turbines, we need to use rotating zones. This requires some additional steps to prepare the CAD before importing the model into the SimScale Workbench. | For the simulation of... 2. Rotating machinery overview (MRF vs sliding mesh) Explains the two CFD approaches used for turbines and similar rotors. simscale.com Turbomachinery Simulation Software | Cloud CFD & FEA | SimScale Simulate turbomachinery in the cloud with SimScale. Run multiphysics analysis on turbines, compressors, and blades to optimize aerodynamic performance. 3. Parametric studies (useful for RPM sweeps) Demonstrates how to vary parameters like rotational velocity across multiple simulations. simscale.com Rotating Zones | Advanced Concepts | SimScale Rotating zones can be used in CFD simulations to model rotating systems, such as turbines, fans, and ventilators. Learn more about their setup here! 4. Turbine tutorial example A step‑by‑step turbine simulation using rotating zones. simscale.com Fluid Flow Through a Water Turbine | Tutorial | SimScale In this advanced tutorial, you will learn how to set up, mesh, and post-process an incompressible water turbine simulation. Join SimScale! These resources cover the standard approach: run multiple simulations at different RPM values and extract torque to build a performance curve.