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Old   December 10, 2010, 06:05
Default Forced vibrations
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Dear All,

I would like to simulate the forced vibration of an axial fan. I have the vibrations modes of it and now I want to let it oscillate in one of the modes. I have 3 excel files containing four columns with the XYZ node positions (1-3) and directional displacemnet XYZ (4) respectively. Then I import it into CFX and multiply it by a forcing function:

A = 5.0e-3 * sin(omega*t)
xDisp = A*mode1.dx(x0,y0,z0)
yDisp = A*mode1.dy(x0,y0,z0)
zDisp = A*mode1.dz(x0,y0,z0)

This works perfectly for a flat plate, however for the case of the fan, which is rotating, the simulation crashes with an error "variable out of bounds".

Does anyone know if Ansys works in rotational reference frame when I specify the mesh deformation using 'specified displacement'? Or does anyone know an alternative reason for the error by looking at the difference between the two cases?

Thank you for your help in advance
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Old   December 13, 2010, 16:30
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Well, some variables are bounded. Typical examples are composition variables.

I have idea what could be out of bounds in your case. Does the error message tells a bit more?
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Old   December 14, 2010, 04:58
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Thanks for your reply! I managed to solve the issue by now. The problem was that I changed to Ansys 13 but still using the setup in 12.1. The program was cheeky enough to change some of my boundary conditions 'in the background' which I did not notice. Unfortunately, the same thing happened to me when changing from 11 to 12. It took 1 month to find out the source of the problem!
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Old   December 14, 2010, 16:53
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Hi Turbomachine,
thats a quite useful information! Thanks for telling us the solution! I will change to 13.0 in the next weeks.
Regards,
Joey2007
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