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-   -   Monitoring moment coefficients for multiple walls with different moment centers? (http://www.cfd-online.com/Forums/fluent/101423-monitoring-moment-coefficients-multiple-walls-different-moment-centers.html)

ali.qasim May 3, 2012 13:23

Monitoring moment coefficients for multiple walls with different moment centers?
 
Hello

I have two vertical-axis wind turbines (2D) separated by a certain distance, rotating about their own axes.

I'd like to monitor the moment coefficients of their airfoils individually. I know I can do this through the Moment Monitor Dialog Box, but it doesn't allow me to choose different moment centers.

Obviously, the two turbines are not rotating about a single point, so I'd like to know how I can specify two points instead of just one.

Please help!

Thanks a lot in advance.

Ali

LuckyTran May 3, 2012 13:28

Quote:

Originally Posted by ali.qasim (Post 359150)
I'd like to monitor the moment coefficients of their airfoils individually. I know I can do this through the Moment Monitor Dialog Box, but it doesn't allow me to choose different moment centers.

Ali, create two separate Moment Monitors. You can then specify the axis individually for each monitor.

ali.qasim May 3, 2012 13:33

Quote:

Originally Posted by LuckyTran (Post 359151)
Ali, create two separate Moment Monitors. You can then specify the axis individually for each monitor.

I didn't know that can be done! How do I do that?

LuckyTran May 3, 2012 14:03

Quote:

Originally Posted by ali.qasim (Post 359155)
I didn't know that can be done! How do I do that?

Uhh, create the first montior. Press ok (or enter if you're using TUI). Create another monitor, press ok. It is straightforward. You can create any number of monitors as you like.

ali.qasim May 3, 2012 14:23

Quote:

Originally Posted by LuckyTran (Post 359165)
Uhh, create the first montior. Press ok (or enter if you're using TUI). Create another monitor, press ok. It is straightforward. You can create any number of monitors as you like.

Hmm. I don't see the option to create. I can only see 'Edit'.

Looks like it has to do with the version. I'm using 12. The Migration Manual for 14 says this is a new feature:
Quote:

Ability to set up multiple monitors in a single case for each one of the following: drag, lift, and moment
Can this still be done in 12? Perhaps through a different route?

LuckyTran May 3, 2012 14:36

Quote:

Originally Posted by ali.qasim (Post 359168)
Hmm. I don't see the option to create. I can only see 'Edit'.

Looks like it has to do with the version. I'm using 12. The Migration Manual for 14 says this is a new feature:


Can this still be done in 12? Perhaps through a different route?

ah-hah, I am using V14. Well in that case you are stuck. You really don't need it anyway. Any reason you need to monitor them this way? You can still print monitors by zone correct? For the sake of monitoring there is no need to have the correct axis. For the purpose of computation you can always report the moment later, or if you need to use the parallel axis theorem to calculate the correct moment.

ali.qasim May 3, 2012 15:15

Quote:

Originally Posted by LuckyTran (Post 359169)
ah-hah, I am using V14. Well in that case you are stuck. You really don't need it anyway. Any reason you need to monitor them this way? You can still print monitors by zone correct? For the sake of monitoring there is no need to have the correct axis. For the purpose of computation you can always report the moment later, or if you need to use the parallel axis theorem to calculate the correct moment.

I'd like to compare the power coefficients - see how much of a difference there is between the upwind and the downwind VAWTs.

Yes, I can print the monitors per zone, but the axis for one will be wrong. And I don't want to do the computation twice.

Hmm.. parallel axis theorem. Rings a bell. You think that'll work for this? I'll have to go read up on that.

LuckyTran May 3, 2012 15:40

Quote:

Originally Posted by ali.qasim (Post 359173)
I'd like to compare the power coefficients - see how much of a difference there is between the upwind and the downwind VAWTs.

Yes, I can print the monitors per zone, but the axis for one will be wrong. And I don't want to do the computation twice.

Hmm.. parallel axis theorem. Rings a bell. You think that'll work for this? I'll have to go read up on that.

Just do the computation. It's only a few button clicks.

ali.qasim May 3, 2012 16:26

Quote:

Originally Posted by LuckyTran (Post 359174)
Just do the computation. It's only a few button clicks.

It'd take me around 36 hours to get the complete computation done. So I'm just trying to solve for the first 10 iterations or so, and will then try to get a correlation between the moment coefficients.

Thanks a lot for your help. Appreciate it.


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