The error message "Divergence detected in AMG solver: temperature" in Ansys Fluent indicates that the solver is having difficulty converging on a solution for the temperature field. Here are some steps you can take to address this issue:
**Understanding the Errors:**
* **Limited Absolute Pressure:** The message "absolute pressure limited to 5.000000e+10 in 32400 cells on zone 2" suggests that the pressure values in some cells (zone 2) are reaching a very high limit. This could be due to an incorrect pressure boundary condition or a physical inconsistency in your model.
* **Limited Turbulent Viscosity:** The message "turbulent viscosity limited to viscosity ratio of 1.000000e+05 in 2150 cells" indicates that the turbulent viscosity is being limited in some cells. This could be happening due to very high or low velocity gradients in those cells.
**Troubleshooting Steps:**
1. **Check Boundary Conditions:** Double-check your pressure boundary conditions for zone 2. Ensure they are set correctly and don't lead to unrealistic pressure values.
2. **Refine Mesh:** A coarse mesh can sometimes lead to convergence issues. Try refining the mesh, particularly in areas with high pressure gradients or complex geometry.
3. **Relaxation Factors:** Adjusting relaxation factors for temperature, pressure, and other relevant variables can sometimes help the solver converge. Start with smaller values and gradually increase them.
4. **Under-Relaxation:** Enable under-relaxation for temperature and pressure. This helps the solver take smaller steps towards the solution during each iteration, potentially avoiding divergence.
5. **Solver Initialization:** Try initializing the solution from a simpler case or a previous converged solution (if available).
6. **Solver Settings:** Experiment with different solver settings like convergence criteria and residuals targets.
7. **Model Geometry:** Review your model geometry for any inconsistencies or sharp corners that might be causing numerical problems.
8. **Material Properties:** Ensure your material properties for temperature and other relevant fields are entered correctly and within reasonable ranges.
**Additional Tips:**
* Consult the Ansys Fluent documentation for detailed information on convergence issues and troubleshooting tips: [https://www.afs.enea.it/project/neptunius/docs/fluent/html/ug/main_pre.htm](https://www.afs.enea.it/project/neptunius/docs/fluent/html/ug/main_pre.htm)
* Search online forums and communities for similar problems and solutions related to your specific case.
* Consider contacting Ansys support for further assistance: [https://www.ansys.com/support](https://www.ansys.com/support)
By systematically troubleshooting these potential causes and adjusting your model setup, you should be able to resolve the divergence issue and achieve a converged temperature solution in Ansys Fluent.
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