Tips to deal with OVERFLOW error in Ansys CFD

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 You've often wondered what could be the reason why your simulation crashes and an overflow error pops up. Today I would like to introduce you  seven tips on what could be causing this error and how to deal with it.


1. Before your analysis, try to perform a trial simulation on a simplified model, both geometrically and physically. If you are dealing with geometry that consists of many elements, create a very simplified diagram on which you will conduct a simplified analysis. If your model includes many physical phenomena, start your trial analysis only with the basic phenomena. After such simplifications, your model will be easier to predict and verify for correctness.

2. Use the method of reducing the solvers that you assume in the simulation. For example, if you have an overflow error and you have radiation involved. In the next iteration, turn off this radiation and check if the error still exists. If you have boundary conditions in your model on which high values ​​are defined, reduce them and check if your analysis starts. Reduce the model until your analysis is stable.

3. Use higher order solvers. If you perform steady-state analysis, use First Order solvers, which will help you achieve convergence of solutions. This can also reduce the risk of an overflow error.

4. Try to reduce the time step for transient analysis. The stability of the simulation is more responsive to the size of the adopted time step than to the quality of the modeled mesh.

5. Try to reduce the accuracy of your analysis for the first steps. If you are able to perform an analysis for the residuals criterion, e.g. 0.1 max you may not be satisfied with the results, but at least you will know what non-physicalities and errors your model is struggling with.

6. Pre-define what order of magnitude of the Reynold number you will be dealing with. Simulations with a low Reynold number do not require a high-quality finite element mesh.

7. Use Ansys Help. There you will find many valuable tips on how to associate given boundary conditions, what are the limitations of some models and what solver settings are preferred for these types of analyzes.

If U want to know how to define user variable in postprocrssing stage in Ansys check it out :

https://howtooansys.blogspot.com/2021/10/how-to-define-user-variable-in-ansys.html

If U want to read more about CFD go links below 

https://howtooansys.blogspot.com/2021/11/investigation-of-influence-of.html

https://howtooansys.blogspot.com/2021/11/thermal-analysis-of-baffles-in-ansys.html

https://howtooansys.blogspot.com/2021/07/how-to-choose-radiation-model-in-ansys.html



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