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josik_1982 December 19, 2010 18:36

help debugging Beam deflection UDF
 
To all those that can help,

I am currently working on a project to use dynamic meshing. the project involves the wake of a cylinder (Karman vortex street) and having a cantilever beam bending in the wake. below is the UDF I have written

I have used the UDF manual and combined info from the CG motion example and the dynamic mesh example. the idea is to use the pressures on the beam to move the beam.

I have attempted multiple options to calculate the force whether by applying a weight/shape function as suggested by a PhD student or by changing the cantilever equation from a point force at the tip to a point force in the center.

every time I run the simulation there is either no bending of the beam or no Karman vortex street. with no dynamic mesh I do get a Karman vortex street.

the fluent setup is laminar, bc's are velocity inlet, pressure outlet - set to 0, outside enclosure wall set to 0 shear, cylinder and beam set to wall with no slip. it is a transient solution based on Strouhal number to get frequency, which correlates to time step. (same way done in the cylinder example.

please note that when i use dynamic mesh preview and a predefined force (cos function) the beam bends as it should.

any help in debugging would be appreciated


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