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O.D.Y. March 21, 2009 15:40

flexible wall movement with udf
Hi @all,

I'm going to simulate the vibration of a rotor blade (axial compressor). I already did it in 2D with simple flap and torsion rigid body motion using the DEFINE_CG_MOTION{} UDF. What I want to do now is to move each node on the blade's surface with respect to a specific flexible modeshape.

Has anyone done something like this before and can anyone give me a hint which UDF I should use?

thanks in advance

paka March 23, 2009 00:10


I cannot help you much, but rather can give you my own idea how I would do it (if I understood you well).

I assume you still want to use rigid body model. I assume vibration is known and you want to study flow around your body, is it right?

I guess you would need to provide data files with nodal motions for each time step or their motion functions if you can provide those.

There is one tutorial for generating periodic waves, I would use this one. It is an empty tank example where one of boundaries move periodically generating waves. I would use the same concept but apply it to your rotor's nodes.

Let me know if you need more details on that tutorial. I hope I did not miss your point.

O.D.Y. March 23, 2009 17:29

Thanks for the hint, I'll take a look at the example asap and see whether it is what I need. And YES you got me right :-) I'm sure that it will be possible to move the nodes in some way, I was only asking myself whether it will be possible to read something like a modeshape file and move each node sinusoidally with its particular value from the modeshape as ampitude. Do you think that this could be possible?


paka March 24, 2009 05:16

Yes, it seems like it is doable, why not? It requires some effort to write UDF, but it seems perfectly fine.

O.D.Y. March 24, 2009 06:01

OK, i'll let u know when I finally "hopefully" succeeded! :-)

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