[tkor]

The impeller is rotated by flowing water.
We are rotating the impeller zone with fluent mrf and simulating it. The moments are checked in the report and the efficiency is calculated from this and the theoretical output. The calculation shows that the efficiency is more than 100%. We can confirm from other information that there is no problem with the calculation method.
The solution is largely convergent.
I do not see any problem with the mesh quality.
The boundary conditions are also considered reasonable.
Do you have any suggestions for improvement?

[Martin_Sz]

It's quite unusual to obtain an efficiency greater than 100% in simulations, as it suggests the system is producing more energy than it consumes, which contradicts the laws of thermodynamics. Here are some additional steps you can take to troubleshoot and potentially improve your ANSYS Fluent simulation:

1. **Recheck the Efficiency Calculation**: Ensure that the efficiency calculation accounts for all forms of energy input and output. This includes checking the work done by the impeller and the energy added to the fluid.

2. **Assess the Simulation Setup**: Verify that the simulation setup, including the Multiple Reference Frame (MRF) settings, is correctly implemented. Make sure that the rotating and stationary zones are properly defined.

3. **Boundary Conditions**: Although you've mentioned that the boundary conditions seem reasonable, it might be helpful to revisit them. Ensure that they accurately represent the physical system and the flow conditions.

4. **Solver Settings**: Review the solver settings to ensure they are appropriate for the type of analysis you're conducting. Sometimes, changing the solver or adjusting the solver settings can lead to more accurate results⁶.

5. **Post-Processing**: Carefully analyze the post-processing results. Look for any anomalies in the flow patterns or unexpected results that could indicate an issue with the simulation.

6. **Consult the Community**: Engage with the ANSYS Fluent community or forums. Other users may have encountered similar issues and could provide insights or solutions⁴.

7. **Tutorials and Documentation**: Review relevant tutorials and documentation for similar cases. These resources can provide guidance on best practices for setting up and running simulations¹²³.

8. **Expert Review**: If possible, have an expert in ANSYS Fluent review your setup. A fresh pair of eyes might spot issues that are not immediately apparent to you.

Remember, simulations are an approximation of reality, and achieving a perfect model is challenging. Continuous refinement and validation against experimental data are key to improving simulation accuracy. If you've exhausted all options and still encounter issues, consider reaching out to ANSYS support for professional assistance.