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UDF node coordinates

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Old   March 20, 2020, 22:52
Lightbulb UDF node coordinates
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Rodrigo Villarreal
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Hi everybody,

I wrote some DEFINE_PROFILE scripts to implement boundary conditions, and they seemed to work fine, but then I realize that all of those conditions are imposed in the face centroid coordinate using the F_CENTROID macro.
Is there a way to impose boundary conditions using the nodal coordinates? If so, which Fluent macro should I use?


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Old   March 21, 2020, 05:45
Default Boundary Condition and F_CENTROID
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Boundary condition is always applied at the centers of the faces. If you want to change that, you will have to write your own solver. The inbuilt solver expects boundary values at the face centers.

F_CENTROID does not apply a profile, it only returns the coordinates of the center of a face. F_PROFILE applies the profile. You can also apply the profile at cell center but not at the nodes. There is no calculations done at the nodes, except during mesh deformation or for the calculation of gradients when node-based gradient is selected. If you want to apply the profile based on the positions of the nodes, then you can just fetch the coordinates of the nodes, calculate the values for the profile based on these coordinates, and apply the profile. However, the value will always be applied at the face center.
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Old   April 10, 2020, 10:55
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Thank you very much for your answer. Now it is very clear to me how to apply the boundary condition properly.
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Old   April 10, 2020, 11:07
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Nice to know that it is clear now.
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