can UDF change the boundary type or turbulence model?
Hi,
I am trying to change the turbulence model I am using depending on the flow speed. For example, I want to use a laminar model when flow speed is 0, and a realizable k-e model when the flow speed is 4 m/s. If possible, how can we do that through UDF? |
It is not possible by UDF. It might be possible by an interaction scheme-UDF, but it seems quite complex.
I can't help you, I don't know a lot about scheme. Anyway, what you are trying, if it is possible and you can implement it, I think that I will not be numerically stable, besides it does not make sense to me. If I where you, I would check in your ANSYS Fluent manual the chapter called "How do I choose my turbulent model", for further information. |
Do you think it would be numerically unstable if I keep changing the models? But if the real condition is like a process have both larminar and turbulent flows at different time, would it be OK if I just use the turbulence model?
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Doesn't the turbulent model give nearly similar results as the laminar model when you apply it to a laminar situation?
In that case I would just use the turbulent model everywhere. You will use some unnecessary computation time on calculating the (small) turbulence in the laminar zones, but I would not worry about that. |
1 Attachment(s)
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The attached figure show the difference. It plots the temperature, the upper one is using a laminar model, the lower one is using a turbulence model. The velocity is 0. All the other boundary conditions are the same. Attachment 36848 |
Did you try the rng k-epsilon?
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