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-   -   earthquake spectrum (http://www.cfd-online.com/Forums/cfx/91221-earthquake-spectrum.html)

enghamed August 4, 2011 01:16

earthquake spectrum
 
Hi all,

I want to model a tank sloshing with respect to earthquake acceleration. How should I define the earthquake spectrum for ansys cfx? I'm doing mesh motion.

Regards;
hamed

ghorrocks August 4, 2011 18:40

CFX cannot model in the frequency domain like modal analysis in FEA. You are going to have to convert it into a displacement versus time and impose that as a mesh motion.

enghamed August 6, 2011 09:32

Thanks for the reply.
If I have a graph of displacment vs time, how should input that to cfx as the mesh displacement?

best regards;

ghorrocks August 7, 2011 08:37

Have a look at the tutorial examples for how to implement moving mesh.

enghamed August 7, 2011 09:48

Thanks. I know how to do mesh motion with a known equation. But know I have the graph of acceleration vs time. If I manage to integrate it and get the plot of displacement vs time, how can I give this as mesh motion. It is not an equation which I could simply enter for mesh motion displacement.

Regards;

ghorrocks August 7, 2011 18:53

If you have the equation of motion then why can't you use it?

enghamed August 7, 2011 20:11

No I don't have the equation. As I said I just have a graph of displacment vs time. I don't know how to implement this graph to mesh motion.

AliTr August 8, 2011 04:24

Quote:

Originally Posted by enghamed (Post 319223)
No I don't have the equation. As I said I just have a graph of displacment vs time. I don't know how to implement this graph to mesh motion.


Create a text file from your data with X Y format, then import it into a CFX function.

enghamed August 8, 2011 08:08

Dear Ali,
Can you please be more specific and guide me on this.
How should I make the text file and then how can I input it in cfx?

Thank you very much.

ghorrocks August 8, 2011 18:26

Use a 1D interpolation function. I set these up by generating the function with some dummy data then editting it in the command editor to include your data points.


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