How to solve below problem in Ansys Fluent Divergence detected in AMG solver: temperature?

on

 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.


Comments

Post a Comment

Popular POSTS

Image

Quick Tip: How to fix Error: GENERAL-CAR-CDR in Ansys (Fluent)

 The error message Error: GENERAL-CAR-CDR: invalid argument [1]: improper list means that there is a problem with the scheme code or the UDF (user-defined function) in your case or data file . Some possible solutions are: Save the case and data file and try to reopen it. Reset the Fluent Setup tab and try opening the mesh. Remesh the geometry and reopen in Fluent. Change the material definition from “Solid” to “Fluid” in Design Modeler. Change the transient to steady if you are using evaporation-condensation as the phase interaction mechanism. Check the syntax of your UDF and make sure it follows the new rules in Fluent 6.2.16 or later. I hope this helps you resolve the error. If you need more assistance, please visit the Ansys Learning Forum or contact Ansys Support . Have a nice day! 😊 Sources: 1. smartadm.ru 2. cfd-online.com 3. forum.ansys.com 4. forum.ansys.com In Polish  BÅ‚Ä…d: GENERAL-CAR-CDR oznacza, że wystÄ…piÅ‚ problem z kodem Scheme w programie Ansys Fluent. Scheme to jÄ™zyk
Image

Types of supports and examples - Ansys Static Structural

Supports are used to represent parts that are not present in the model but are interacting with it. Supports help truncate the domain, which helps in efficiently obtaining numerically accurate results without modeling parts of the geometry that are not of primary interest. There are different types of support available, among which you need to choose the appropriate one for your analysis. Here are some of the common types of supports and their explanations: - **Fixed Support**: This type of support constrains all the degrees of freedom of the selected entity (body, face, or edge). It means that the entity cannot move or rotate in any direction. Fixed support is equivalent to applying zero displacement to all directions. Fixed support is useful for modeling rigid connections or supports that do not allow any movement. For example, you can use fixed support to model a bolted joint or a clamped beam. - **Displacement Support**: This type of support specifies a zero or non-zero displacemen
Image

How to define porosity (porous medium) in Ansys CFD (Fluent, CFX)

 To model porosity in ANSYS Fluent , you need to define the porous zone and the porous media properties in the setup. You can follow these steps: In the Fluent interface, go to the Cell Zone Conditions panel and select the zone that you want to make porous. Check the Porous Zone option and click Edit. In the Porous Zone panel, you can choose between two methods to specify the porous media resistance: the Superficial Velocity method or the Physical Velocity method. The Superficial Velocity method uses the superficial velocity (the velocity of the fluid if there were no porosity) to calculate the pressure drop across the porous zone. The Physical Velocity method uses the physical velocity (the velocity of the fluid inside the pores) to calculate the pressure drop across the porous zone. You can also choose between isotropic or anisotropic porosity, depending on whether the porosity is uniform or varies in different directions. Depending on the method and the type of porosity you choose,
Image

💥💥💥 How to model in PrePoMAX ?

PrePoMax is a freeware pre- and postprocessor for open-source Finite Element Analysis solver CalculiX 1 . It offers a user-friendly GUI and supports many features provided by the CalculiX solver. To model in PrePoMax, you need to follow these general steps: Create or import a geometry using the Geometry menu 2 . Generate a mesh using the Mesh menu 2 . Define the FE model using the Model , Property , Interaction , Initial Condition , and Step menus 2 . Export the input file for CalculiX using the File menu 2 . Run the analysis using the Tools menu 2 . Import the results file and visualize the output using the View menu 2 . You can find more detailed instructions and examples in the PrePoMax documentation 1 and video tutorials 1 . I hope this helps you get started with PrePoMax. 😊 The official PrePoMax website 1 has a section on documentation, where you can download the PrePoMax manual in PDF format. The manual covers the basic features and workflow of PrePoMax, as well as some